means The vast bodies of saltwater that cover most of Earth's surface, divided by convention into the Pacific, Atlantic, Indian, Southern, and Arctic.

from From the Greek 'Okeanos,' the great river the ancients believed encircled the entire flat world — and also a Titan god, son of sky and earth, whose waters wrapped everything. The word flowed into Latin as 'oceanus,' then through Old French into English. So every time you say 'ocean,' you're invoking a primordial deity the Greeks imagined as the boundary of all things known.