means the rhythmic throbbing of the arteries as the heart pumps blood, felt as a beat under the skin — or, more broadly, any steady recurring rhythm or surge.

from From Latin 'pulsus,' meaning a beating or striking, the past participle of 'pellere,' to push or drive — the same root that gives us 'propel,' 'compel,' and 'expel.' The heartbeat, then, is literally a push: blood driven through you, knocking at the walls of your arteries. (The other 'pulse' — lentils, beans, peas — is a separate word entirely, from Latin 'puls,' a thick porridge, and unrelated to the beating kind.)