Oceanic means “to do with the ocean” — the great salt water that covers most of the Earth. Scientists like this word: oceanic water, an oceanic current, oceanic crust (the rock under the deep sea, which is not the same as the rock under the land), an oceanic climate (weather shaped by the sea). It is a bit more formal than just using ocean as a describing word, as in ocean water or ocean fish. Though actually, those everyday ocean + noun pairs are often the more natural choice in speech; oceanic sounds like a textbook or a science report. People sometimes stretch it for things that feel as wide or as deep as the sea. There is also a special use in language study: Oceanic languages are a family of languages spoken on many Pacific islands. That still ties back to the ocean those islands sit in.