Definition of envelope in English:

envelope

noun ˈɛnvələʊpˈɒnvələʊp

1A flat paper container with a sealable flap, used to enclose a letter or document.
信封
Example sentencesExamples
- It is enclosed in a sealed envelope along with this letter.
- Many of those in the line clutched envelopes containing documents such as birth and marriage certificates, along with photographs.
- In the latest incident, at 12.30 pm on Sunday, a 93-year-old woman had a brown envelope containing documents stolen.
- Each letter had a small number in the corner on the backside of the letter; in the envelope was just paper, nothing else.
- For years, the yellowing envelope and the letter it contained were kept solely for nostalgia value, despite being pressed into service as a humble bookmark.
- Residents will have until January 6 to return the ballot paper in the pre-paid envelope which will come with the letter.
- Declined manuscripts will be returned if stamped, self-addressed envelopes are enclosed with submissions.
- The soldier would then enclose his ballot and the thrice-signed document in an envelope.
- Completed questionnaires were mailed back to the research team in self-addressed, stamped envelopes enclosed with the surveys.
- New product areas would include drawing paper, envelopes, greetings cards and stationary folders.
- They are all instant communications that are far less bother than putting pen to paper, finding an envelope, licking the flap, sticking on a stamp and popping it in a post box.
- What made it worse was they had not paid enough postage for the weight of paper the envelopes contained.
- The pens and pencils were in a can on the corner, a small box contained crisp white envelopes, extra paper was in a folder, and a stack of manuscripts sat on the far side of the desk.
- The letters contained a smaller envelope each, with the defendant's name on three of these and a further two names on the other two.
- She was typing letters, envelopes and handwriting appointments onto paper planners that were stuffed in ragged edged file folders.
- Each survey was enclosed in a stamped envelope, addressed to the researcher.
- Returning envelopes containing ballot papers are also distinctively marked to aid sorting.
- To maintain secrecy, the return ballot paper envelope had a detachable flap on which the voter filled in their details.
- The paperwork involved is horrendous - ballot papers, witness forms, pre-paid envelopes, ballot paper envelopes and explanatory notes.
- My boss handed me the envelope containing the necessary papers.
Synonyms
wrapper, wrapping, wrap, sleeve, cover, covering
casing, case
2A covering or containing structure or layer.
封皮，封套；外表，外壳；包裹物
the external envelope of the swimming pool
游泳池的外罩。
Example sentencesExamples
- The laboratory blocks within the overall envelope are linked by walkways, bridges and meeting platforms.
- Its strong external envelope, made from several distinct Titanium shells, will protect it from the dangers of a long flight in space's hostile environment.
- Providers know that they have to work within the envelope of resources earned by the insurance plan.
- Suppose the atmosphere of our planet to be surrounded by an envelope impervious to light, with an aperture on the sunward side, through which a solar beam could enter and cross our atmosphere.
- Located at the outer edges of the building and formed by the external envelope, these lofts are moulded by folds that are conspicuous both inside and out.
- Construction of the house commenced on-site on October 14 and the structural envelope was erected in an incredible five days.
- No one can do any work within the structural envelope of the building.
- A sea-urchin egg is surrounded by a protective covering known as the vitelline envelope, which in turn is covered with a thick coat of jelly.
- The observed tide is a result of the rotation of the Earth within the envelope of the two deformations, which remain fixed in orientation relative to the Moon and Sun.
- But it is noticeable that, even within the overall envelope of European culture, it is all too easy for despotism, of one sort or another, to become the ruling paradigm.
- This provides a visually intricate envelope to the external public space and assists night-time security to the main entrance.
- In this approach they have the patient stay within the envelope and only use a comfortable range of energy expenditure.
- In addition to serving as a semipermeable layer, the envelope in cucumber, muskmelon, and other cucurbitaceous seeds is known to act as the primary barrier to radicle emergence.
- In summer the fan is reversed, cooling the building by drawing fresh air through louvres in the external envelope.
- The bones of the ankles and feet also took on a paddle shape, and individual digits were closely packed within a streamlining envelope of soft tissue.
- We checked in with the frigate, made sure her winds were within our approach envelope, and landed at 0757.
- It was however still possible to tell the location of the nuclear envelope to within 1-2 m.
- ‘I wanted to hint at the modern interior that's behind the historic external envelope,’ he says.
- Concrete grade beams spanning between the caissons were used to accommodate external envelope conditions and elevator pits.
- Then I fly the boom around to make sure it can fly within the prescribed envelope.
1. 2.1 The outer metal or glass housing of a vacuum tube, electric light, etc.
  （真空管或电灯等的）泡
  the switch itself is a glass envelope filled with rare gases and containing two contacts
  Example sentencesExamples
  The glass envelope gently undulates to follow the site as it moves along the riverfront; it seems to express the flow of the water.
  The presumption that the glass envelopes of these bulbs function as cutoff filters to remove short wavelength radiation was unsubstantiated.
  As you know from replacing light bulbs, there is a large, thin, frosted glass envelope in the familiar light bulb shape.
  The other great problem of glass envelopes is their transparency not only to light, but to much of the electro-magnetic spectrum.
  Synonyms
  cover, case, shell, sheath, sheathing, wrapper, wrapping, sleeve, jacket, housing, capsule, folder
2. 2.2 The structure within a balloon or non-rigid airship containing the gas.
  （气球或软式飞艇的）气囊
  Example sentencesExamples
  They hold open the envelope as the balloon is inflated.
  He led a team of 12 in Glastonbury, which designed and built the balloon envelope and flight platform.
  The team plays an important role in ensuring the balloon is prepared and filled to suit the timing of the launch and to ensure the envelope is ready for take off.
  At this time of day, the world is wonderfully peaceful - just the sound of distant burners pushing hot air into the envelopes of nearby balloons and songbirds below.
3. 2.3Microbiology A membrane which forms the outer layer of certain viruses.
  〔微生物〕包膜，外膜，被膜
  Example sentencesExamples
  The cell envelope of gram-positive bacteria consists of the cytoplasmic membrane and a cell wall.
  The insertion of the fusion peptide in the host membrane provides the necessary link between the viral envelope and the cell membrane.
  The departing viruses therefore have an envelope that can fuse with the membranes of nearby cells, allowing the virus to enter.
  Evidence suggesting the existence of multiple import pathways at the outer envelope membrane for different classes of precursor proteins has been presented.
  As the infection progresses, however, each sequential form of the virus envelope increasingly escapes detection.
4. 2.4Electronics A curve joining the successive peaks of a modulated wave.
  〔电子〕包络（曲）线
  Example sentencesExamples
  Noise, when used with a vocal modulator, traces the envelope of the vocal with wideband noise.
5. 2.5Mathematics A curve or surface tangent to each of a family of curves or surfaces.
  〔数〕包络线（或面）
  Example sentencesExamples
  Jacob Bernoulli also discovered a general method to determine evolutes of a curve as the envelope of its circles of curvature.
  We looked at it, and it's just a sine wave, an envelope of minimum and maximum, with the width of the wave showing the time in boom vs. the time in recession.
  To compare the deuterium contents of the different peptides, an averaged mass was obtained by centroiding the envelope of isotopic peaks.
  In particular he constructed the tangent plane and exhibited the surface as an envelope of planes.
  The idea of an envelope of a family of lines had not been mentioned either.

Phrases

the back of an envelope

Used in reference to calculations or plans of the most sketchy kind.
（指估计或计划）最粗略的一类
a proposal drawn up on the back of an envelope
一项草拟的粗略提议。
Example sentencesExamples
- I said it was because I believed in the theatre as a figurative art, not something contrived on the back of an envelope.
- But it was hardly an overnight plot devised on the back of an envelope.
- 20 years ago, the song was fine - the whole point of the project was a sudden response to a terrible situation, so it didn't matter that the song was written in ten minutes on the back of an envelope.
- Simple calculations on the back of an envelope will do for a start.
- The probe began life as a sketch drawn on the back of an envelope during a night at the pub.
- It's much higher than the age pension, but a quick calculation on the back of an envelope will tell you that it's not going to allow many of the activities we might hope for in retirement - travel, entertainment, books and the like.
- The Scottish Socialist Party wants to get rid of the council tax and have done some calculations on the back of an envelope in order to redistribute the burden of local taxation.
- It is a well known fact that all inventors get their first ideas on the back of an envelope.
- For once, the proposals - addressing parents, school, punishment, drug addiction, targets, and police paperwork - don't look as if they were written on the back of an envelope.
- Visiting a clean water project, he did a swift calculation on the back of an envelope and announced that the whole country could be provided with water for $25 million.

push the envelope (or the edge of the envelope)

Approach or extend the limits of what is possible.
〈非正式〉接近（或达到）极致
these are extremely witty and clever stories that consistently push the envelope of TV comedy
这些故事极其诙谐和巧妙，总是将电视喜剧推向极致。
Example sentencesExamples
- I don't push the envelope just for the sake of pushing the envelope.
- The evening news was a little strange but I could tell the newsroom was starting to get a feel for the limits now and were pushing the envelope as far as they could.
- You have to be able to push the edge of the envelope, but you have to be able to do it in a way that you can see what the community of users' reaction is.
- We're trying to push the envelope as much as possible.
- But the trend is to go to the extreme, push the envelope and be as outrageous as possible.
- He's a coach - like every other coach - who pushes the envelope as far as possible to create a winning advantage.
- The Film Board has always been here to push the envelope, to push the film language, and this is where we excel, what we are good at.
- He pushed the envelope of possibility with his art, but pushes the boundaries of acceptable conduct as well.
- To say that he bends the rules, pushes the envelope and extends the possibilities of fiction is to state only part of the case.
- On more than one occasion, she says, publishers have approached her to push the envelope - to write a novel of her own.

Origin

Mid 16th century (in the sense 'wrapper, enveloping layer'; originally as envelope): from French enveloppe, from envelopper 'envelop'. The sense 'covering of a letter' dates from the early 18th century.

An envelope was originally any kind of wrapper or covering, not just something to put a letter in. It is from the same word as envelop, ‘to wrap up or surround’, from Old French envoluper the en- meaning ‘in’, but the origin of the rest is lost. To push the envelope is to go up to, or beyond, the limits of what is possible, an idea that comes from aeronautics. Since the Second World War the envelope or flight envelope has been the set of combinations of speed, altitude, and range within which a particular kind of aircraft can fly safely. If a test pilot is pushing the envelope he is flying the plane at the very limits of its performance. The phrase came into wider circulation after 1979 following its use in The Right Stuff, a book by American author Tom Wolfe about the early days of the American space programme, later made into an Oscar-winning film.

Definition of envelope in US English:

envelope

noun

1A flat paper container with a sealable flap, used to enclose a letter or document.
信封
Example sentencesExamples
- The soldier would then enclose his ballot and the thrice-signed document in an envelope.
- The pens and pencils were in a can on the corner, a small box contained crisp white envelopes, extra paper was in a folder, and a stack of manuscripts sat on the far side of the desk.
- Completed questionnaires were mailed back to the research team in self-addressed, stamped envelopes enclosed with the surveys.
- For years, the yellowing envelope and the letter it contained were kept solely for nostalgia value, despite being pressed into service as a humble bookmark.
- Many of those in the line clutched envelopes containing documents such as birth and marriage certificates, along with photographs.
- Returning envelopes containing ballot papers are also distinctively marked to aid sorting.
- Declined manuscripts will be returned if stamped, self-addressed envelopes are enclosed with submissions.
- To maintain secrecy, the return ballot paper envelope had a detachable flap on which the voter filled in their details.
- Residents will have until January 6 to return the ballot paper in the pre-paid envelope which will come with the letter.
- My boss handed me the envelope containing the necessary papers.
- New product areas would include drawing paper, envelopes, greetings cards and stationary folders.
- They are all instant communications that are far less bother than putting pen to paper, finding an envelope, licking the flap, sticking on a stamp and popping it in a post box.
- What made it worse was they had not paid enough postage for the weight of paper the envelopes contained.
- The paperwork involved is horrendous - ballot papers, witness forms, pre-paid envelopes, ballot paper envelopes and explanatory notes.
- She was typing letters, envelopes and handwriting appointments onto paper planners that were stuffed in ragged edged file folders.
- Each survey was enclosed in a stamped envelope, addressed to the researcher.
- The letters contained a smaller envelope each, with the defendant's name on three of these and a further two names on the other two.
- It is enclosed in a sealed envelope along with this letter.
- In the latest incident, at 12.30 pm on Sunday, a 93-year-old woman had a brown envelope containing documents stolen.
- Each letter had a small number in the corner on the backside of the letter; in the envelope was just paper, nothing else.
Synonyms
wrapper, wrapping, wrap, sleeve, cover, covering
2A covering or containing structure or layer.
封皮，封套；外表，外壳；包裹物
the external envelope of the swimming pool
游泳池的外罩。
Example sentencesExamples
- A sea-urchin egg is surrounded by a protective covering known as the vitelline envelope, which in turn is covered with a thick coat of jelly.
- But it is noticeable that, even within the overall envelope of European culture, it is all too easy for despotism, of one sort or another, to become the ruling paradigm.
- The laboratory blocks within the overall envelope are linked by walkways, bridges and meeting platforms.
- In addition to serving as a semipermeable layer, the envelope in cucumber, muskmelon, and other cucurbitaceous seeds is known to act as the primary barrier to radicle emergence.
- In this approach they have the patient stay within the envelope and only use a comfortable range of energy expenditure.
- Located at the outer edges of the building and formed by the external envelope, these lofts are moulded by folds that are conspicuous both inside and out.
- ‘I wanted to hint at the modern interior that's behind the historic external envelope,’ he says.
- This provides a visually intricate envelope to the external public space and assists night-time security to the main entrance.
- No one can do any work within the structural envelope of the building.
- The bones of the ankles and feet also took on a paddle shape, and individual digits were closely packed within a streamlining envelope of soft tissue.
- Its strong external envelope, made from several distinct Titanium shells, will protect it from the dangers of a long flight in space's hostile environment.
- Construction of the house commenced on-site on October 14 and the structural envelope was erected in an incredible five days.
- Providers know that they have to work within the envelope of resources earned by the insurance plan.
- The observed tide is a result of the rotation of the Earth within the envelope of the two deformations, which remain fixed in orientation relative to the Moon and Sun.
- Then I fly the boom around to make sure it can fly within the prescribed envelope.
- We checked in with the frigate, made sure her winds were within our approach envelope, and landed at 0757.
- It was however still possible to tell the location of the nuclear envelope to within 1-2 m.
- Concrete grade beams spanning between the caissons were used to accommodate external envelope conditions and elevator pits.
- In summer the fan is reversed, cooling the building by drawing fresh air through louvres in the external envelope.
- Suppose the atmosphere of our planet to be surrounded by an envelope impervious to light, with an aperture on the sunward side, through which a solar beam could enter and cross our atmosphere.
1. 2.1 The outer metal or glass housing of a vacuum tube, electric light, etc.
  （真空管或电灯等的）泡
  Example sentencesExamples
  The presumption that the glass envelopes of these bulbs function as cutoff filters to remove short wavelength radiation was unsubstantiated.
  The other great problem of glass envelopes is their transparency not only to light, but to much of the electro-magnetic spectrum.
  As you know from replacing light bulbs, there is a large, thin, frosted glass envelope in the familiar light bulb shape.
  The glass envelope gently undulates to follow the site as it moves along the riverfront; it seems to express the flow of the water.
  Synonyms
  cover, case, shell, sheath, sheathing, wrapper, wrapping, sleeve, jacket, housing, capsule, folder
2. 2.2 The structure within a balloon or nonrigid airship containing the gas.
  （气球或软式飞艇的）气囊
  Example sentencesExamples
  The team plays an important role in ensuring the balloon is prepared and filled to suit the timing of the launch and to ensure the envelope is ready for take off.
  He led a team of 12 in Glastonbury, which designed and built the balloon envelope and flight platform.
  At this time of day, the world is wonderfully peaceful - just the sound of distant burners pushing hot air into the envelopes of nearby balloons and songbirds below.
  They hold open the envelope as the balloon is inflated.
3. 2.3Microbiology A membrane forming the outer layer of certain viruses.
  〔微生物〕包膜，外膜，被膜
  Example sentencesExamples
  Evidence suggesting the existence of multiple import pathways at the outer envelope membrane for different classes of precursor proteins has been presented.
  The departing viruses therefore have an envelope that can fuse with the membranes of nearby cells, allowing the virus to enter.
  As the infection progresses, however, each sequential form of the virus envelope increasingly escapes detection.
  The insertion of the fusion peptide in the host membrane provides the necessary link between the viral envelope and the cell membrane.
  The cell envelope of gram-positive bacteria consists of the cytoplasmic membrane and a cell wall.
4. 2.4Electronics A curve joining the successive peaks of a modulated wave.
  〔电子〕包络（曲）线
  Example sentencesExamples
  Noise, when used with a vocal modulator, traces the envelope of the vocal with wideband noise.
5. 2.5Mathematics A curve or surface tangent to each of a family of curves or surfaces.
  〔数〕包络线（或面）
  Example sentencesExamples
  To compare the deuterium contents of the different peptides, an averaged mass was obtained by centroiding the envelope of isotopic peaks.
  Jacob Bernoulli also discovered a general method to determine evolutes of a curve as the envelope of its circles of curvature.
  The idea of an envelope of a family of lines had not been mentioned either.
  We looked at it, and it's just a sine wave, an envelope of minimum and maximum, with the width of the wave showing the time in boom vs. the time in recession.
  In particular he constructed the tangent plane and exhibited the surface as an envelope of planes.
6. 2.6Astronomy The nebulous covering of the head of a comet; coma.
  Example sentencesExamples
  These circumstellar envelopes are indeed progenitors of planetary nebulae.

Phrases

push the envelope (or the edge of the envelope)

Approach or extend the limits of what is possible.
〈非正式〉接近（或达到）极致
these are extremely witty and clever stories that consistently push the envelope of TV comedy
这些故事极其诙谐和巧妙，总是将电视喜剧推向极致。
Example sentencesExamples
- We're trying to push the envelope as much as possible.
- But the trend is to go to the extreme, push the envelope and be as outrageous as possible.
- He's a coach - like every other coach - who pushes the envelope as far as possible to create a winning advantage.
- On more than one occasion, she says, publishers have approached her to push the envelope - to write a novel of her own.
- To say that he bends the rules, pushes the envelope and extends the possibilities of fiction is to state only part of the case.
- I don't push the envelope just for the sake of pushing the envelope.
- The Film Board has always been here to push the envelope, to push the film language, and this is where we excel, what we are good at.
- The evening news was a little strange but I could tell the newsroom was starting to get a feel for the limits now and were pushing the envelope as far as they could.
- He pushed the envelope of possibility with his art, but pushes the boundaries of acceptable conduct as well.
- You have to be able to push the edge of the envelope, but you have to be able to do it in a way that you can see what the community of users' reaction is.

Origin

Mid 16th century (in the sense ‘wrapper, enveloping layer’; originally as envelope): from French enveloppe, from envelopper ‘envelop’. The sense ‘covering of a letter’ dates from the early 18th century.

单词	envelope
释义	Definition of envelope in English: envelope noun ˈɛnvələʊpˈɒnvələʊp 1A flat paper container with a sealable flap, used to enclose a letter or document. 信封 Example sentencesExamples It is enclosed in a sealed envelope along with this letter. Many of those in the line clutched envelopes containing documents such as birth and marriage certificates, along with photographs. In the latest incident, at 12.30 pm on Sunday, a 93-year-old woman had a brown envelope containing documents stolen. Each letter had a small number in the corner on the backside of the letter; in the envelope was just paper, nothing else. For years, the yellowing envelope and the letter it contained were kept solely for nostalgia value, despite being pressed into service as a humble bookmark. Residents will have until January 6 to return the ballot paper in the pre-paid envelope which will come with the letter. Declined manuscripts will be returned if stamped, self-addressed envelopes are enclosed with submissions. The soldier would then enclose his ballot and the thrice-signed document in an envelope. Completed questionnaires were mailed back to the research team in self-addressed, stamped envelopes enclosed with the surveys. New product areas would include drawing paper, envelopes, greetings cards and stationary folders. They are all instant communications that are far less bother than putting pen to paper, finding an envelope, licking the flap, sticking on a stamp and popping it in a post box. What made it worse was they had not paid enough postage for the weight of paper the envelopes contained. The pens and pencils were in a can on the corner, a small box contained crisp white envelopes, extra paper was in a folder, and a stack of manuscripts sat on the far side of the desk. The letters contained a smaller envelope each, with the defendant's name on three of these and a further two names on the other two. She was typing letters, envelopes and handwriting appointments onto paper planners that were stuffed in ragged edged file folders. Each survey was enclosed in a stamped envelope, addressed to the researcher. Returning envelopes containing ballot papers are also distinctively marked to aid sorting. To maintain secrecy, the return ballot paper envelope had a detachable flap on which the voter filled in their details. The paperwork involved is horrendous - ballot papers, witness forms, pre-paid envelopes, ballot paper envelopes and explanatory notes. My boss handed me the envelope containing the necessary papers. Synonyms wrapper, wrapping, wrap, sleeve, cover, covering casing, case 2A covering or containing structure or layer. 封皮，封套；外表，外壳；包裹物 the external envelope of the swimming pool 游泳池的外罩。 Example sentencesExamples The laboratory blocks within the overall envelope are linked by walkways, bridges and meeting platforms. Its strong external envelope, made from several distinct Titanium shells, will protect it from the dangers of a long flight in space's hostile environment. Providers know that they have to work within the envelope of resources earned by the insurance plan. Suppose the atmosphere of our planet to be surrounded by an envelope impervious to light, with an aperture on the sunward side, through which a solar beam could enter and cross our atmosphere. Located at the outer edges of the building and formed by the external envelope, these lofts are moulded by folds that are conspicuous both inside and out. Construction of the house commenced on-site on October 14 and the structural envelope was erected in an incredible five days. No one can do any work within the structural envelope of the building. A sea-urchin egg is surrounded by a protective covering known as the vitelline envelope, which in turn is covered with a thick coat of jelly. The observed tide is a result of the rotation of the Earth within the envelope of the two deformations, which remain fixed in orientation relative to the Moon and Sun. But it is noticeable that, even within the overall envelope of European culture, it is all too easy for despotism, of one sort or another, to become the ruling paradigm. This provides a visually intricate envelope to the external public space and assists night-time security to the main entrance. In this approach they have the patient stay within the envelope and only use a comfortable range of energy expenditure. In addition to serving as a semipermeable layer, the envelope in cucumber, muskmelon, and other cucurbitaceous seeds is known to act as the primary barrier to radicle emergence. In summer the fan is reversed, cooling the building by drawing fresh air through louvres in the external envelope. The bones of the ankles and feet also took on a paddle shape, and individual digits were closely packed within a streamlining envelope of soft tissue. We checked in with the frigate, made sure her winds were within our approach envelope, and landed at 0757. It was however still possible to tell the location of the nuclear envelope to within 1-2 m. ‘I wanted to hint at the modern interior that's behind the historic external envelope,’ he says. Concrete grade beams spanning between the caissons were used to accommodate external envelope conditions and elevator pits. Then I fly the boom around to make sure it can fly within the prescribed envelope. 2.1 The outer metal or glass housing of a vacuum tube, electric light, etc. （真空管或电灯等的）泡 the switch itself is a glass envelope filled with rare gases and containing two contacts Example sentencesExamples The glass envelope gently undulates to follow the site as it moves along the riverfront; it seems to express the flow of the water. The presumption that the glass envelopes of these bulbs function as cutoff filters to remove short wavelength radiation was unsubstantiated. As you know from replacing light bulbs, there is a large, thin, frosted glass envelope in the familiar light bulb shape. The other great problem of glass envelopes is their transparency not only to light, but to much of the electro-magnetic spectrum. Synonyms cover, case, shell, sheath, sheathing, wrapper, wrapping, sleeve, jacket, housing, capsule, folder 2.2 The structure within a balloon or non-rigid airship containing the gas. （气球或软式飞艇的）气囊 Example sentencesExamples They hold open the envelope as the balloon is inflated. He led a team of 12 in Glastonbury, which designed and built the balloon envelope and flight platform. The team plays an important role in ensuring the balloon is prepared and filled to suit the timing of the launch and to ensure the envelope is ready for take off. At this time of day, the world is wonderfully peaceful - just the sound of distant burners pushing hot air into the envelopes of nearby balloons and songbirds below. 2.3Microbiology A membrane which forms the outer layer of certain viruses. 〔微生物〕包膜，外膜，被膜 Example sentencesExamples The cell envelope of gram-positive bacteria consists of the cytoplasmic membrane and a cell wall. The insertion of the fusion peptide in the host membrane provides the necessary link between the viral envelope and the cell membrane. The departing viruses therefore have an envelope that can fuse with the membranes of nearby cells, allowing the virus to enter. Evidence suggesting the existence of multiple import pathways at the outer envelope membrane for different classes of precursor proteins has been presented. As the infection progresses, however, each sequential form of the virus envelope increasingly escapes detection. 2.4Electronics A curve joining the successive peaks of a modulated wave. 〔电子〕包络（曲）线 Example sentencesExamples Noise, when used with a vocal modulator, traces the envelope of the vocal with wideband noise. 2.5Mathematics A curve or surface tangent to each of a family of curves or surfaces. 〔数〕包络线（或面） Example sentencesExamples Jacob Bernoulli also discovered a general method to determine evolutes of a curve as the envelope of its circles of curvature. We looked at it, and it's just a sine wave, an envelope of minimum and maximum, with the width of the wave showing the time in boom vs. the time in recession. To compare the deuterium contents of the different peptides, an averaged mass was obtained by centroiding the envelope of isotopic peaks. In particular he constructed the tangent plane and exhibited the surface as an envelope of planes. The idea of an envelope of a family of lines had not been mentioned either. Phrases the back of an envelope Used in reference to calculations or plans of the most sketchy kind. （指估计或计划）最粗略的一类 a proposal drawn up on the back of an envelope 一项草拟的粗略提议。 Example sentencesExamples I said it was because I believed in the theatre as a figurative art, not something contrived on the back of an envelope. But it was hardly an overnight plot devised on the back of an envelope. 20 years ago, the song was fine - the whole point of the project was a sudden response to a terrible situation, so it didn't matter that the song was written in ten minutes on the back of an envelope. Simple calculations on the back of an envelope will do for a start. The probe began life as a sketch drawn on the back of an envelope during a night at the pub. It's much higher than the age pension, but a quick calculation on the back of an envelope will tell you that it's not going to allow many of the activities we might hope for in retirement - travel, entertainment, books and the like. The Scottish Socialist Party wants to get rid of the council tax and have done some calculations on the back of an envelope in order to redistribute the burden of local taxation. It is a well known fact that all inventors get their first ideas on the back of an envelope. For once, the proposals - addressing parents, school, punishment, drug addiction, targets, and police paperwork - don't look as if they were written on the back of an envelope. Visiting a clean water project, he did a swift calculation on the back of an envelope and announced that the whole country could be provided with water for $25 million. push the envelope (or the edge of the envelope) Approach or extend the limits of what is possible. 〈非正式〉接近（或达到）极致 these are extremely witty and clever stories that consistently push the envelope of TV comedy 这些故事极其诙谐和巧妙，总是将电视喜剧推向极致。 Example sentencesExamples I don't push the envelope just for the sake of pushing the envelope. The evening news was a little strange but I could tell the newsroom was starting to get a feel for the limits now and were pushing the envelope as far as they could. You have to be able to push the edge of the envelope, but you have to be able to do it in a way that you can see what the community of users' reaction is. We're trying to push the envelope as much as possible. But the trend is to go to the extreme, push the envelope and be as outrageous as possible. He's a coach - like every other coach - who pushes the envelope as far as possible to create a winning advantage. The Film Board has always been here to push the envelope, to push the film language, and this is where we excel, what we are good at. He pushed the envelope of possibility with his art, but pushes the boundaries of acceptable conduct as well. To say that he bends the rules, pushes the envelope and extends the possibilities of fiction is to state only part of the case. On more than one occasion, she says, publishers have approached her to push the envelope - to write a novel of her own. Origin Mid 16th century (in the sense 'wrapper, enveloping layer'; originally as envelope): from French enveloppe, from envelopper 'envelop'. The sense 'covering of a letter' dates from the early 18th century. An envelope was originally any kind of wrapper or covering, not just something to put a letter in. It is from the same word as envelop, ‘to wrap up or surround’, from Old French envoluper the en- meaning ‘in’, but the origin of the rest is lost. To push the envelope is to go up to, or beyond, the limits of what is possible, an idea that comes from aeronautics. Since the Second World War the envelope or flight envelope has been the set of combinations of speed, altitude, and range within which a particular kind of aircraft can fly safely. If a test pilot is pushing the envelope he is flying the plane at the very limits of its performance. The phrase came into wider circulation after 1979 following its use in The Right Stuff, a book by American author Tom Wolfe about the early days of the American space programme, later made into an Oscar-winning film. noun.1 phr. Definition of envelope in US English: envelope noun 1A flat paper container with a sealable flap, used to enclose a letter or document. 信封 Example sentencesExamples The soldier would then enclose his ballot and the thrice-signed document in an envelope. The pens and pencils were in a can on the corner, a small box contained crisp white envelopes, extra paper was in a folder, and a stack of manuscripts sat on the far side of the desk. Completed questionnaires were mailed back to the research team in self-addressed, stamped envelopes enclosed with the surveys. For years, the yellowing envelope and the letter it contained were kept solely for nostalgia value, despite being pressed into service as a humble bookmark. Many of those in the line clutched envelopes containing documents such as birth and marriage certificates, along with photographs. Returning envelopes containing ballot papers are also distinctively marked to aid sorting. Declined manuscripts will be returned if stamped, self-addressed envelopes are enclosed with submissions. To maintain secrecy, the return ballot paper envelope had a detachable flap on which the voter filled in their details. Residents will have until January 6 to return the ballot paper in the pre-paid envelope which will come with the letter. My boss handed me the envelope containing the necessary papers. New product areas would include drawing paper, envelopes, greetings cards and stationary folders. They are all instant communications that are far less bother than putting pen to paper, finding an envelope, licking the flap, sticking on a stamp and popping it in a post box. What made it worse was they had not paid enough postage for the weight of paper the envelopes contained. The paperwork involved is horrendous - ballot papers, witness forms, pre-paid envelopes, ballot paper envelopes and explanatory notes. She was typing letters, envelopes and handwriting appointments onto paper planners that were stuffed in ragged edged file folders. Each survey was enclosed in a stamped envelope, addressed to the researcher. The letters contained a smaller envelope each, with the defendant's name on three of these and a further two names on the other two. It is enclosed in a sealed envelope along with this letter. In the latest incident, at 12.30 pm on Sunday, a 93-year-old woman had a brown envelope containing documents stolen. Each letter had a small number in the corner on the backside of the letter; in the envelope was just paper, nothing else. Synonyms wrapper, wrapping, wrap, sleeve, cover, covering 2A covering or containing structure or layer. 封皮，封套；外表，外壳；包裹物 the external envelope of the swimming pool 游泳池的外罩。 Example sentencesExamples A sea-urchin egg is surrounded by a protective covering known as the vitelline envelope, which in turn is covered with a thick coat of jelly. But it is noticeable that, even within the overall envelope of European culture, it is all too easy for despotism, of one sort or another, to become the ruling paradigm. The laboratory blocks within the overall envelope are linked by walkways, bridges and meeting platforms. In addition to serving as a semipermeable layer, the envelope in cucumber, muskmelon, and other cucurbitaceous seeds is known to act as the primary barrier to radicle emergence. In this approach they have the patient stay within the envelope and only use a comfortable range of energy expenditure. Located at the outer edges of the building and formed by the external envelope, these lofts are moulded by folds that are conspicuous both inside and out. ‘I wanted to hint at the modern interior that's behind the historic external envelope,’ he says. This provides a visually intricate envelope to the external public space and assists night-time security to the main entrance. No one can do any work within the structural envelope of the building. The bones of the ankles and feet also took on a paddle shape, and individual digits were closely packed within a streamlining envelope of soft tissue. Its strong external envelope, made from several distinct Titanium shells, will protect it from the dangers of a long flight in space's hostile environment. Construction of the house commenced on-site on October 14 and the structural envelope was erected in an incredible five days. Providers know that they have to work within the envelope of resources earned by the insurance plan. The observed tide is a result of the rotation of the Earth within the envelope of the two deformations, which remain fixed in orientation relative to the Moon and Sun. Then I fly the boom around to make sure it can fly within the prescribed envelope. We checked in with the frigate, made sure her winds were within our approach envelope, and landed at 0757. It was however still possible to tell the location of the nuclear envelope to within 1-2 m. Concrete grade beams spanning between the caissons were used to accommodate external envelope conditions and elevator pits. In summer the fan is reversed, cooling the building by drawing fresh air through louvres in the external envelope. Suppose the atmosphere of our planet to be surrounded by an envelope impervious to light, with an aperture on the sunward side, through which a solar beam could enter and cross our atmosphere. 2.1 The outer metal or glass housing of a vacuum tube, electric light, etc. （真空管或电灯等的）泡 Example sentencesExamples The presumption that the glass envelopes of these bulbs function as cutoff filters to remove short wavelength radiation was unsubstantiated. The other great problem of glass envelopes is their transparency not only to light, but to much of the electro-magnetic spectrum. As you know from replacing light bulbs, there is a large, thin, frosted glass envelope in the familiar light bulb shape. The glass envelope gently undulates to follow the site as it moves along the riverfront; it seems to express the flow of the water. Synonyms cover, case, shell, sheath, sheathing, wrapper, wrapping, sleeve, jacket, housing, capsule, folder 2.2 The structure within a balloon or nonrigid airship containing the gas. （气球或软式飞艇的）气囊 Example sentencesExamples The team plays an important role in ensuring the balloon is prepared and filled to suit the timing of the launch and to ensure the envelope is ready for take off. He led a team of 12 in Glastonbury, which designed and built the balloon envelope and flight platform. At this time of day, the world is wonderfully peaceful - just the sound of distant burners pushing hot air into the envelopes of nearby balloons and songbirds below. They hold open the envelope as the balloon is inflated. 2.3Microbiology A membrane forming the outer layer of certain viruses. 〔微生物〕包膜，外膜，被膜 Example sentencesExamples Evidence suggesting the existence of multiple import pathways at the outer envelope membrane for different classes of precursor proteins has been presented. The departing viruses therefore have an envelope that can fuse with the membranes of nearby cells, allowing the virus to enter. As the infection progresses, however, each sequential form of the virus envelope increasingly escapes detection. The insertion of the fusion peptide in the host membrane provides the necessary link between the viral envelope and the cell membrane. The cell envelope of gram-positive bacteria consists of the cytoplasmic membrane and a cell wall. 2.4Electronics A curve joining the successive peaks of a modulated wave. 〔电子〕包络（曲）线 Example sentencesExamples Noise, when used with a vocal modulator, traces the envelope of the vocal with wideband noise. 2.5Mathematics A curve or surface tangent to each of a family of curves or surfaces. 〔数〕包络线（或面） Example sentencesExamples To compare the deuterium contents of the different peptides, an averaged mass was obtained by centroiding the envelope of isotopic peaks. Jacob Bernoulli also discovered a general method to determine evolutes of a curve as the envelope of its circles of curvature. The idea of an envelope of a family of lines had not been mentioned either. We looked at it, and it's just a sine wave, an envelope of minimum and maximum, with the width of the wave showing the time in boom vs. the time in recession. In particular he constructed the tangent plane and exhibited the surface as an envelope of planes. 2.6Astronomy The nebulous covering of the head of a comet; coma. Example sentencesExamples These circumstellar envelopes are indeed progenitors of planetary nebulae. Phrases push the envelope (or the edge of the envelope) Approach or extend the limits of what is possible. 〈非正式〉接近（或达到）极致 these are extremely witty and clever stories that consistently push the envelope of TV comedy 这些故事极其诙谐和巧妙，总是将电视喜剧推向极致。 Example sentencesExamples We're trying to push the envelope as much as possible. But the trend is to go to the extreme, push the envelope and be as outrageous as possible. He's a coach - like every other coach - who pushes the envelope as far as possible to create a winning advantage. On more than one occasion, she says, publishers have approached her to push the envelope - to write a novel of her own. To say that he bends the rules, pushes the envelope and extends the possibilities of fiction is to state only part of the case. I don't push the envelope just for the sake of pushing the envelope. The Film Board has always been here to push the envelope, to push the film language, and this is where we excel, what we are good at. The evening news was a little strange but I could tell the newsroom was starting to get a feel for the limits now and were pushing the envelope as far as they could. He pushed the envelope of possibility with his art, but pushes the boundaries of acceptable conduct as well. You have to be able to push the edge of the envelope, but you have to be able to do it in a way that you can see what the community of users' reaction is. Origin Mid 16th century (in the sense ‘wrapper, enveloping layer’; originally as envelope): from French enveloppe, from envelopper ‘envelop’. The sense ‘covering of a letter’ dates from the early 18th century. noun.1 phr.
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