periodic event

the periodic passage of groups of animals (especially birds or fishes) from one region to another for feeding or breeding

a single complete execution of a periodically repeated phenomenon

an event that repeats

the daily event of the sun rising above the horizon

the daily event of the sun sinking below the horizon

the rhythmic contraction and expansion of the arteries with each beat of the heart

the periodic rise and fall of the sea level under the gravitational pull of the moon

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)

several repetitions of a melodic phrase in different keys

a periodically repeated sequence of events

something (especially a game) that is played again

happening again (especially at regular intervals)

the widening of the chambers of the heart between two contractions when the chambers fill with blood

the contraction of the chambers of the heart (especially the ventricles) to drive blood into the aorta and pulmonary artery

an instance of rapid strong pulsation (of the heart)

the tide when the water is highest

the lowest (farthest) ebb of the tide

the tide while water is flowing out

the occurrence of incoming water (between a low tide and the following high tide)

a tide that runs in the same direction as the wind is blowing

the occurrence of relatively still water at the turn of the (low) tide

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