1911 Encyclopædia Britannica/Period

PERIOD (Gr. περίοδος, a going or way round, circuit, περί, round, and ὁδός, way, road), a circuit or course of time, a cycle; particularly the duration of time in which a planet revolves round its sun, or a satellite round its primary, a definite or indefinite recurring interval of time marked by some special or peculiar character, e.g. in history, literature, art, &c.; it is so used of a division of geological time. Particular uses of the word are for the various phases through which a disease passes, the termination or conclusion of any course of events, the pause at the end of a completed sentence, and the mark (.) used to signify the same (see Punctuation).