Definition of "Period" :

noun: 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."

noun: the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause

noun: an amount of time

"A time period of 30 years."

noun: the end or completion of something

"Death put a period to his endeavors."

noun: a unit of geological time during which a system of rocks formed

"Ganoid fishes swarmed during the earlier geological periods."

noun: (ice hockey) one of three divisions into which play is divided in hockey games

noun: the interval taken to complete one cycle of a regularly repeating phenomenon