an event that recurs at intervals

move or swing from side to side regularly

the complete cycle of events in the heart from the beginning of one heart beat to the beginning of the next; an electrical impulse conducted through the heart muscle that constricts the atria which is followed by constriction of the ventricles

a cycle (of expansion and compression) of an idealized reversible heat engine that does work without loss of heat

one complete cycle of operations (as by a computer)

a recurring cycle (beginning at menarche and ending at menopause) in which the endometrial lining of the uterus prepares for pregnancy; if pregnancy does not occur the lining is shed at menstruation