A single beat in a repeating rhythm. A pulse says something is alive and running.
Latin pulsus (a beating, a push), from pellere (to push, to drive, to beat); a pulse is named for the striking itself, not for what is struck.
A single beat in a repeating rhythm, proof that something is alive and still running. The root's push is the honest description: a pulse is not a state, it is a strike repeated.