1. 一段时间；时期
    A period is a length of time.

    e.g. This crisis might last for a long period of time.
           这次危机可能持续很长时间。
    e.g. ...a period of a few months.
           几个月时间

2. （个人、组织或社会的）阶段，时期，时代
    A period in the life of a person, organization, or society is a length of time which is remembered for a particular situation or activity.

    e.g. ...a period of economic good health and expansion...
           经济健康发展并且不断扩张的一段时期
    e.g. He went through a period of wanting to be accepted...
           有一段时间他很想被人接受。

3. （历史上的）阶段，时期
    A particular length of time in history is sometimes called a period. For example, you can talk about the Victorian period or the Elizabethan period in Britain.

    e.g. ...the Roman period...
           罗马帝国时代
    e.g. No reference to their existence appears in any literature of the period.
           这一时期的文学作品中都没有提及他们的存在。

4. （服装、家具、乐器）过去的，古代的，具有某个时代特征的
    Period costumes, furniture, and instruments were made at an earlier time in history, or look as if they were made then.

period在线翻译

    e.g. ...dressed in full period costume.
           穿着宽松的古装
    e.g. ...replicas of period instruments.
           古乐器的复制品

5. （练习、训练、学习的）时间，时段
    Exercise, training, or study periods are lengths of time that are set aside for exercise, training, or study.

period

    e.g. They accompanied him during his exercise periods.
           练习的时候他们陪着他。

6. 课；课时；节
    At a school or college, a period is one of the parts that the day is divided into during which lessons or other activities take place.

    e.g. ...periods of private study.
           自习课
    e.g. ...taking his scripts to school in order to learn the lines in free periods.
           把他的剧本带到学校以便空闲的时候背台词

7. 月经
    When a woman has a period, she bleeds from her womb. This usually happens once a month, unless she is pregnant.

8. 到此为止；不再说了
    Some people say period after stating a fact or opinion when they want to emphasize that they are definite about something and do not want to discuss it further.

    e.g. I don't want to do it, period.
           我不想做，这事就到此为止吧。

9. 句号
    A period is the punctuation mark (.) which you use at the end of a sentence when it is not a question or an exclamation.