ETYM Latin periodus, Greek, a going round, a way round, a circumference, a period of time; peri round, about + hodos a way: cf. French période.
1. A stage in the history of a culture having a definable place in space and time; SYN. historic period, historical period.
2. A time of life characterized as a distinct phase.
3. A unit of geological time during which a system of rocks formed; SYN. geological period.
4. One of (usually) three or four sections of play in various sports.
5. The end or completion of something.
6. The interval taken to complete one cycle of a regularly repeating phenomenon.

Of, relating to, or representing a particular historical period

The length of time required for an oscillation to complete one full cycle. For an oscillating electrical signal, the period is the time between waveform repetitions. If f is the frequency of oscillation in hertz, and t is the period in seconds, then t = 1/f. See the illustration.
In physics, the time taken for one complete cycle of a repeated sequence of events. For example, the time taken for a pendulum to swing from side to side and back again is the period of the pendulum.

In musical analysis, one of the basic structural units of melody, consisting of a pair of phrases, the first often ending with an “imperfect cadence” (“half close”), the second often ending with a “perfect cadence” (“full close”).

Another name for menstruation; see menstrual cycle.

In chemistry, a horizontal row of elements in the periodic table. There is a gradation of properties along each period, from metallic (group I, the alkali metals) to nonmetallic (group VII, the halogens).

A punctuation mark ) placed at the end of a declarative sentence to indicate a full stop or after abbreviations; SYN. point, full stop, stop, full point.
Punctuation mark (.). The term “period” is universally understood in English and is the preferred usage in North America; “full stop” is the preferred term in the uk. The period has two functions: to mark the end of a sentence and to indicate that a word has been abbreviated. It is also used in mathematics to indicate decimals and is then called a point.