1A length or portion of time.
1.1 A portion of time in the life of a nation, civilization, etc. characterized by the same prevalent features or conditions.
1.2 A major division of geological time that is a subdivision of an era and is itself subdivided into epochs.
1.3 Each of the set divisions of the day in a school allocated to a lesson or other activity.
1.4 Each of the divisions of the playing time of a sporting event.
2.1Astronomy The time taken by a celestial object to rotate about its axis, or to make one circuit of its orbit.
2.2Mathematics The interval between successive equal values of a periodic function.
3A 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.
4North American A punctuation mark (.) used at the end of a sentence or an abbreviation; a full stop.
4.1informal Added to the end of a statement to indicate that no further discussion is possible or desirable.
A set of elements occupying a horizontal row in the periodic table.
A complex sentence, especially one consisting of several clauses, constructed as part of a formal speech or oration.
6.1Music A complete idea, typically consisting of two or four phrases.
attributive Belonging to or characteristic of a past historical time, especially in style or design.
dated Put an end to.
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 century.