(mathematics) Any function whose value repeats after the regular addition of a period to its independent variable; i.e., a function ƒ such that, for some positive constant p, ƒ(x + p) = ƒ(x) for all x.

(physics) A characteristic of the transition of a system or process from regular motion to chaos, in which the period of one of its parameters is seen to double.

A relatively brief period when a new leader is given greater leeway with respect to changes he or she wishes to make.

(historical) The period of Egyptian history from the end of the Third Intermediate Period to the conquest of Egypt by Alexander the Great (the 26th through 31st dynasties), characterized by alternating periods of native and Persian rule.

Synonym of time period

The length of time during which an activity occurs or a condition remains. It may be measured either in seconds or in millions of years, depending upon the nature of the activity of condition being considered.

plural of periodic inequality

(astronomy) A disturbance in the motion of a planet due to its position in its orbit relative to another planet.

plural of periodic month

Synonym of tropical month