Definition of period:
an amount of time; "a time period of 30 years"; "hastened the period of time of his recovery"; "Picasso's blue period"
the interval taken to complete one cycle of a regularly repeating phenomenon
(ice hockey) one of three divisions into which play is divided in hockey games
a unit of geological time during which a system of rocks formed; "ganoid fishes swarmed during the earlier geological periods"
the end or completion of something; "death put a period to his endeavors"; "a change soon put a period to my tranquility"
the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause; "the women were sickly and subject to excessive menstruation"; "a woman does not take the gout unless her menses be stopped"--Hippocrates; "the semen begins to appear in males and to be emitted at the same time of life that the catamenia begin to flow in females"--Aristotle
a punctuation mark (.) placed at the end of a declarative sentence to indicate a full stop or after abbreviations; "in England they call a period a stop"