| Noun | 1. | systole - the contraction of the chambers of the heart (especially the ventricles) to drive blood into the aorta and pulmonary arteryheartbeat, beat, pulse, pulsation - the rhythmic contraction and expansion of the arteries with each beat of the heart; "he could feel the beat of her heart" extrasystole - a premature systole resulting in a momentary cardiac arrhythmia | |