1A strip of wood or stone forming the bottom of a doorway and crossed in entering a house or room.

1. 1.1in singular A point of entry or beginning.
   入门；开端；开始
   she was on the threshold of a dazzling career

   她正要开始灿烂的职业前程。

   Example sentencesExamples

   • Although only on the threshold of life, Raymond and Ellen - who were outgoing and fun loving - had touched the hearts of young and old alike.
   • For a city that is on the threshold of a major expansion, Mr. Monayee's is a gentle reminder that the city should not lose its soul in the search for economic prosperity.
   • In the present exhibition the seven participating artists are young and on the threshold of their careers hoping to make works that in time would translate into blue-chip art.
   • After spreading destruction all over Russia, Hitler's hordes reached Stalingrad, where they believed they were on the threshold of final victory and hunkered down for the winter.
   • Thanks to the convergence of the information and genome sciences revolution, we are already on the threshold of isolating and characterizing virtually all useful genes.
   • But on the threshold of great age he was no nearer an answer.
   • We are on the threshold of a new historical event: Bulgaria's accession to the European Union.
   • The judge, Mr Justice Wakerley, told Rafaqat: ‘You took the life of your young cousin on the threshold of her marriage.’
   • Recording a verdict of misadventure, deputy coroner Carolyn Singleton said she had heard evidence of a young man on the threshold of his adult life who, for whatever reason, decided to dabble with lighter fuel.
   • We're on the threshold of a brand new beginning.
   • The autobiography covers the author's early years up to the threshold of university.
   • On the threshold of 2004, what are your expectations on a global scale in view of modern challenges such as international terrorism and international community's efforts to combat it?
   • They play urban refugees - an unhappily married man and a coffee-shop girl burdened by her ill father - on the threshold of potential love.
   • Bulgaria is on the threshold of becoming a part of the North Atlantic Alliance; what is your comment on this, against the background of Austria's policy of neutrality?
   • A student on the threshold of a new life at university killed himself with a massive cyanide overdose because of the acne that had ‘tormented’ him.
   • We, his grandparents, see Gareth not just as a grandson, but a friend, a fine young man on the threshold of a wonderful life, which was so tragically cut short, on one of the happiest days of his life.
   • Although he was not yet wholly able to make a living from sales of his work, he had grown close to the leading surrealists and was on the threshold of fame following his first solo exhibition.
   • We are on the threshold of a state of social anarchy.
   • ‘We don't want to talk about it but we are on the threshold of winning the league for the first time ever,’ says Campbell, ensuring that he breathes deeply enough.
   • Young students are on the threshold of adulthood, walking through the door to their future.

   Synonyms

   start, starting point, beginning, brink, verge, edge, dawn, birth, origin, inception, conception, opening, launch, inauguration, institution, initiation, debut, creation, day one

   informal kick-off

   formal commencement
2. 1.2 The beginning of an airport runway on which an aircraft is attempting to land.
   机场跑道入口；跑道头
   Example sentencesExamples

   • The aircraft crossed the threshold at 50 feet and the landing lights illuminated the numbers and fixed distance markers.
   • As I turned off the runway, I saw my wingman's landing light disappear into the fog at about 50 feet above the runway threshold.
   • Maj Hunter executed a flawless short-field landing and touched down on-speed just past the threshold.
   • It is designed to fly under the 4,000 ft threshold used by commercial aircraft.
   • The airplane crashed approximately two miles southeast of the Runway 27 threshold.
   • The aircraft hit the embankment short of the threshold, sliding up it, turning through 90-deg and coming to a stop.
   • BA has held preliminary discussions with BAA, which owns Heathrow, about making changes to the infrastructure, to allow for the new landing threshold.
   • The jet stopped 100 feet short of the threshold on the 10,000-foot runway.
   • Runway 14 began atop a steeply sloping terrace with an abrupt drop-off at the approach end, departure end and left side of the threshold.
   • After we passed and began our second missed approach at 400 feet, I saw what appeared to be the first 50 feet or so of the runway threshold.
   • Every additional knot of airspeed when crossing the threshold will cause the aircraft to float an additional 1,000 feet down the runway.
   • Try not to think of taxiing as just driving to the runway threshold.
   • The XP - 38 slammed into a golf course short of the runway threshold and Kelsey was luck to escape with cuts and bruises.
   • The Bonanza crossed the runway threshold while the helicopter was still about 250 feet from a planned touchdown point of 1500 feet down the runway.
   • Just before coming abeam the runway threshold I began a continuous finals turn, Spitfire style.
   • Not a single word was spoken as we neared the runway threshold, the throttle still wide open.
   • Flight 1420 touched down about 2,000 ft from the runway threshold, to the right of the runway centerline, and moved rapidly to the right.

2The magnitude or intensity that must be exceeded for a certain reaction, phenomenon, result, or condition to occur or be manifested.

1. 2.1 The maximum level of radiation or a concentration of a substance considered to be acceptable or safe.
   （物质辐射或浓度的）安全阈值
   their water would meet the safety threshold of 50 milligrams of nitrates per litre

   Example sentencesExamples

   • What can be done if the concentration of metallic elements rises above the toxic threshold, particularly those that have no known function in the body?
   • This finding will make ongoing state and federal legislative efforts to craft safe exposure thresholds in response to growing public concern and litigation over mold more difficult, policy analysts say.
   • The Commission is of the view that the existing thresholds allow concentrations that have significant cross-border effects to fall outside the Regulation.
   • Lowering the PSA threshold for proceeding to prostate biopsy would increase the risks of overdiagnosing and overtreating clinically unimportant disease.
   • There seems to be a threshold plasma concentration below which symptoms may become apparent.
   • The WHO-proposed threshold for Der p1 allergen concentration is 2 [micro] g/gm dust.
   • The clinical risks of sensitivity and specificity also should be considered in identifying the threshold glycemic level.
   • There is a threshold below which radiation is safe and above which it becomes dangerous.
   • Finally, salbutamol pretreatment might hasten lidocaine absorption and increase peak lidocaine plasma concentrations toward the toxic threshold.
   • Moreover, there is an indication that the threshold of sucrose concentration may be lower in the bundle sheath than in the mesophyll.
   • The threshold for CEMA concentrations toxic to tobacco cells was found to be 30-35 g ml - 1.
   • This information was essential in permitting an accurate estimation of the safety thresholds of inhaled corticosteroid use and in eliminating confounding by use of oral corticosteroids.
   • The hunchback gene is switched on only when bicoid protein, a transcription factor, is present at a certain threshold concentration.
   • Exposure concentrations were well below threshold limit values, and hepatotoxicity was not predicted for these compounds.
   • Evaluation of substances for which a threshold limit did not exist were then carried out.
   • At a conservative calculation, around 250,000 people are currently exposed to levels above the accepted safety thresholds.
   • There is a threshold of ATP concentration which stimulated the binding remarkably.
   • When it comes to carcinogens and toxins, for example, Priceless assumes that there is no safe threshold.
   • We considered drivers negative if their urine tests were negative or their blood concentrations below these thresholds.
   • However, if the threshold for normal cholesterol is also applied half of the population would be considered at risk by the early age of 24 years.

   Synonyms

   lower limit, starting point, minimum, margin

   Psychology limen
2. 2.2 The level at which one starts to feel or react to something.
   he has a low boredom threshold

   Example sentencesExamples

   • Thus, units with preinspiratory discharge patterns may have comparatively low thresholds to stimulation by central chemoreceptor afferent inputs relative to inspiratory units.
   • A few years after college, a freak accident - and one seriously low threshold for boredom - redirected Jaime's life.
   • Moreover, there is no evidence based recommendation of a risk threshold above which no attempt should be made.
   • Richard is the high school superstar, with a rich daddy and a low boredom threshold.
   • Houseguests with low boredom thresholds can take advantage of all that Ayrshire has to offer; Burns's Cottage, Ayr Racecourse and the golf courses at Royal Troon, Prestwick and Turnberry are all within easy reach.
   • Kagan and his colleagues have hypothesized that inhibited children have a lower threshold for sympathetic activation.
   • They also reported that the simple cells of young rats showed lower light flicker thresholds as well as a preference for slower movement speeds compared to complex and hypercomplex cells.
   • Conditioned to expect immediate gratification, these youth have shorter attention spans and also a low threshold for boredom.
   • In the case of sugar, which is picked up by receptors on the tongue, flavor enhancers bind to the receptors and lower their threshold for stimulation, creating the same taste with less sugar.
   • If you have a low threshold for boredom, you'll probably end up with a ‘kerchief.
   • Lower pain thresholds and potentially lower thresholds for other nociceptive stimuli such as HTS would be consistent with systemic nociceptive dysfunction in CFS.
   • Tissue congestion and inflammation tend to sensitize nerve endings and lower the threshold for stimuli.
   • Patients with head injury should therefore not be pushed to return to demanding activities too quickly, and there should be a low threshold for seeking a specialist opinion or undertaking psychometric assessment.
   • Professionals should have a low threshold for enquiring about mental health issues in children as parents rarely raise these concerns.
   • A limit is place on the threshold that will be tolerated.
   • These mediators lower the nociceptor threshold, making the receptors more responsive to painful stimuli.
   • Absence makes your boredom threshold lower, as well as your heart sore.
   • In contrast, introverts are thought to be more socially conforming, more sensitive to reinforcement, have lower sensory thresholds, and therefore feel pain more easily.
3. 2.3 A level, rate, or amount at which something comes into effect.
   〈主英〉起始点；（税的）起征点
   the inheritance tax threshold

   Example sentencesExamples

   • The threshold for the higher rate tax of 40 per cent - which is at present pegged at stg £32,785 - is also expected to rise.
   • This is the threshold at which workers start to pay income tax.
   • We have also increased the payroll and land tax thresholds that free up many small businesses from the burden of payroll and land taxes altogether.
   • Without doubt, the 50 per cent increase in stamp duty rates and thresholds will have the single most negative impact.
   • He predicted that the party would next promise to cut inheritance tax and the threshold for income tax.
   • Inheritance Tax thresholds will rise by more than inflation over the next three years to £300,000 by the 2007/08 tax year.
   • Mr Flemming noted that small-scale farmers were not eligible for VAT registration, as they did not earn sufficient amounts to reach the VAT threshold.
   • The amount is below the threshold for inheritance tax, so there's no tax due immediately.
   • Britain and the North's inheritance tax thresholds are far less generous than Irish rates, and many beneficiaries in the Republic could end up paying the higher rate on property bequeathed to them.
   • The Treasurer has announced new thresholds for marginal tax rates, which will cut personal income tax by $14.7 billion over the next four years.
   • I have also decided to radically restructure the rates and the thresholds for all three classes of beneficiaries and to increase the threshold for probate tax.
   • The National Insurance rates and limits for 2005-6 were confirmed by the chancellor in the pre-budget report, as were tax credit rates, thresholds and limits.
   • Consider raising the small business tax and surtax thresholds for passenger vehicles and increasing the property transfer tax exemption.
   • For example, you could have two parents who both work but who each earn just below the threshold for higher rate income tax.
   • Donaldson also may raise the threshold for hedge-fund investment, now $200,000 in income or a net worth of $1 million.
   • Most of the bills would ban prepayment penalties, put caps on points, and establish Annual Percentage Rate thresholds.
   • So tonight Mr Speaker, what we have been led to believe and what those newspapers will demand is the income tax thresholds, the rates, the costings and how they will be paid for.
   • On vacant land, the thresholds are $140,000 for metropolitan areas and $110,000 in regional areas.
   • In Spain, income tax is payable on the gross rents at a flat rate of 25 per cent while in Portugal, no tax-free threshold or tax credit is available in calculating assessable income.
   • Unlike inheritance tax, which typically rises in line with the Retail Price Index, stamp duty thresholds do not rise automatically with each Budget.