systole

noun4

1. •
   The rhythmic contraction of the heart, by which blood is driven through the arteries.

   • A double systole catapulted him into full consciousness again, and he promised his uncorrected self that he would limit his daily ration of cigarettes to a couple of heartbeats. — 1972
2. •
   The contraction of the contractile vesicles in certain algae, plasmodia, and zoospores.
3. •
   (rhetoric) A shortening of a naturally long vowel.
4. •
   The shortest noncontractible loop on a compact metric space.