Period (from Greek περίοδος) or periodic may refer to: Language and literature Full stop, a punctuation mark indicating the end of a sentence or phrase Periodic sentence, a sentence that isn't grammatically complete until its end The final book in Dennis Cooper's George Miles cycle of novels Period piece describes creative works set in a particular era. Science and mathematics Menstruation, a phase of the menstrual cycle in which the uterine lining'… (More on Period)