1
- a length or portion of time（一段）时间, 时期, 阶段：
he had long periods of depression
他几次陷入长时间的消沉
the ale will be available for a limited period
麦芽酒只供应有限的一段时间
the period 1977-85.
1977-1985年这一时期。
1.1
- a portion of time in the life of a person, nation, or civilization characterized by the same prevalent features or conditions阶段; 时代：
the early medieval period.
中世纪的早期。
1.2
- one of the set divisions of the day in a school allocated to a lesson or other activity学时, 课时。
1.3
- with modifier a set period of time during which a particular activity takes place周期, 期：
the training period is between 16 and 18 months.
训练期是16到18个月。
1.4
- each of the intervals into which the playing time of a sporting event is divided（体育比赛的）局。
1.5
- a major division of geological time that is a subdivision of an era and is itself subdivided into epochs, corresponding to a system in chronostratigraphy（地质年代划分的）纪。
2
- Physics the interval of time between successive occurrences of the same state in an oscillatory or cyclic phenomenon, such as a mechanical vibration, an alternating current, a variable star, or an electromagnetic wave【物理】（振动或循环的）周期。
2.1
- Astronomy the time taken by a celestial object to rotate about its axis, or to make one circuit of its orbit【天文】自转（或公转）周期。
2.2
- Mathematics the interval between successive equal values of a periodic function【数】（周期函数的）周期。
3
- （亦作menstrual period）a flow of blood and other material from the lining of the uterus, lasting for a few days and occurring in sexually mature women who are not pregnant at intervals of about one lunar month until the menopause（妇女的）经期。
4
- chiefly N. Amer. a full stop〈主北美〉句号, 句点。
4.1
- informal added to the end of a statement to indicate that no further discussion is possible or desirable〈非正式〉到此为止, 就这样（常用于陈述末尾, 表示无法或无需再讨论）：
he is the sole owner of the trademark, period.
他是那商标的唯一所有人, 就是这样。
5
- Chemistry a set of elements occupying a horizontal row in the periodic table【化】周期元素。
6
- Rhetoric a complex sentence, especially one consisting of several clauses, constructed as part of a formal speech or oration【修辞】完整句。
6.1
- Music a complete idea, typically consisting of two or four phrases【乐】乐段, 乐节。
attrib.
- belonging to or characteristic of a past historical time, especially in style or design（尤指风格或设计）属于过去某一特定历史时期的; 具有过去某一特定历史时期特点的：
a splendid selection of period furniture.
古老家具精选。
短语
put a period to
- dated put an end to; bring to a conclusion〈旧〉使结束, 终止：
in dry climates, the onset of summer drought may put a period to plant activity.
在干燥的气候条件下, 夏季干旱的开始就可能使植物丧失活力。
词源
late Middle English （denoting the time during which something, especially a disease, runs its course）： from Old French periode, via Latin from Greek periodos 'orbit, recurrence, course', from peri- 'around' + hodos 'way, course'. The sense 'portion of time' dates from the early 17th cent.