period

English period comes from Middle English periode, borrowed through Middle French periode and Medieval Latin periodus from Ancient Greek períodos, meaning a circuit, orbit, or recurring interval of time. That Greek word joins peri- ("around") with hodós ("way"), so it literally means a way around.

Its Greek sense of a circuit or recurring interval — like a planet's orbit — carried through Latin and French into English, where it settled into meaning a stretch of time, and eventually the mark that closes a sentence. In English it also displaced older native words like tide and elde, which had covered similar ground.

It's built from the same root as hodós, "way," the second half of words describing paths or routes; period itself is literally a "way around."