Period or periodic may refer to: Language and literature Full stop, a punctuation mark indicating the end of a sentence or phrase Periodic sentence (rhetoric), a sentence that isn't grammatically complete until its end The final book in Dennis Cooper's George Miles cycle of novels Science and mathematics Menstruation, a phase of the menstrual cycle in which the uterine lining is shed Orbital period, a concept in astronomy Period (gene), a gene in Drosophila involved in regulating circadi… (More on Period)