What is Period?

Legal Definition
Any point, space or division of time. "The word 'period' has its etymological meaning, but it also has a distinctive signification, according to the subject with which it may be used in connection. It may mean any portion of complete time, from a thousand years or less to the period of a day; and when used to designate an act to be done or to be begun, though its completion may take an uncertain time, as, for instance, the act of exportation, it must mean the day on which the exportation commences or it would be an unmeaning and useless word in its connection in the statute." Sampson v. Peas-lce, 20 How. 579, 15 In Ed. 1022.
-- Black's Law Dictionary