period (a length of time)
period (a length of time in history seen as a single coherent entity; an epoch, era)
period (the length of time during which the same characteristics of a periodic phenomenon recur, such as the repetition of a wave or the rotation of a planet)
period (each of the divisions into which a school day is split, allocated to a given subject or activity)
period (female menstruation; an episode of this)
period (a complete sentence, especially one expressing a single thought or making a balanced, rhythmic whole)
period (the length of an interval over which a periodic function, periodic sequence or repeating decimal repeats; often the least such length)
period (two phrases (an antecedent and a consequent phrase))
period (a geochronologic unit of millions to tens of millions of years; a subdivision of an era, and subdivided into epochs)