<p><strong>Noun</strong></p><ul><li>a rather large interval of time that is meaningful in the life of a person, in history, etc., because of its particular characteristics: a period of illness; a period of great profitability for a company; a period of social unrest in Germany.</li><li>any specified division or portion of time: poetry of the period from 1603 to 1660.</li><li>a round of time or series of years by which time is measured.</li><li>a round of time marked by the recurrence of some phenomenon or occupied by some recurring process or action.</li><li>the point of completion of a round of time or of the time during which something lasts or happens.</li><li>Education. a specific length of time during school hours that a student spends in a classroom, laboratory, etc., or has free.</li><li>any of the parts of equal length into which a game is divided.</li><li>the time during which something runs its course.</li><li>the present time.</li><li>the point or character (.) used to mark the end of a declarative sentence, indicate an abbreviation, etc.; full stop.</li><li>a full pause, as is made at the end of a complete sentence; full stop.</li><li>a sentence, especially a well-balanced, impressive sentence: the stately periods of Churchill.</li><li>a periodic sentence.</li><li>an occurrence of menstruation.</li><li>a time of the month during which menstruation occurs.</li><li>Geology. the basic unit of geologic time, during which a standard rock system is formed: comprising two or more epochs and included with other periods in an era.</li><li>Physics. the duration of one complete cycle of a wave or oscillation; the reciprocal of the frequency.</li><li>Music. a division of a composition, usually a passage of eight or sixteen measures, complete or satisfactory in itself, commonly consisting of two or more contrasted or complementary phrases ending with a conclusive cadence.</li><li>Astronomy. Also called period of rotation. the time in which a body rotates once on its axis.</li><li>Also called period of revolution. the time in which a planet or satellite revolves once about its primary.</li><li>Mathematics. periodic.</li><li>Classical Prosody. a group of two or more cola.</li></ul><p><strong>Adjective</strong></p><ul><li>noting, pertaining to, evocative of, imitating, or representing a historical period or the styles current during a specific period of history: period costumes; a period play.</li></ul><p><strong>Interjection</strong></p><ul><li>(used by a speaker or writer to indicate that a decision is irrevocable or that a point is no longer discussable): I forbid you to go, period.</li></ul>