An interval of time characterized by the occurrence of a certain condition, event, or phenomenon: a period of economic prosperity. An interval of time characterized by the prevalence of a specified culture, ideology, or technology: artifacts of the pre-Columbian period. An interval regarded as a distinct evolutionary or developmental phase: Picasso's early career is divided into his blue period and rose period. Geology A unit of time, longer than an epoch and shorter than an era. Any of various arbitrary units of time, especially: Any of the divisions of the academic day. Sports & Games A division of the playing time of a game. Physics & Astronomy The time interval between two successive occurrences of a recurrent event or phases of an event; a cycle: the period of a satellite's orbit. An instance or occurrence of menstruation. A point or portion of time at which something is ended; a completion or conclusion. The full pause at the end of a spoken sentence. A punctuation mark ( . ) indicating a full stop, placed at the end of declarative sentences and other statements thought to be complete, and after many abbreviations. A sentence of several carefully balanced clauses in formal writing. A metrical unit of quantitative verse consisting of two or more cola. An analogous unit or division of classical Greek or Latin prose. Music A group of two or more phrases within a composition, often made up of 8 or 16 measures and terminating with a cadence. Mathematics The least interval in the range of the independent variable of a periodic function of a real variable in which all possible values of the dependent variable are assumed. Mathematics A group of digits separated by commas in a written number. Mathematics The number of digits that repeat in a repeating decimal. For example, 1/7 = 0.142857142857 . . . has a six-digit period. Chemistry A sequence of elements arranged in order of increasing atomic number and forming one of the horizontal rows in the periodic table. Of, belonging to, or representing a certain historical age or time: a period piece; period furniture. Used to emphasize finality, as when expressing a decision or an opinion: You're not going to the movies tonight, period!