So it's kind of a complicated question — "gravity" did not refer to a force until Newton's approach (1687), but the notion of gravity as the "heaviness" is much older than that. Using gravity to refer to the fact that massive objects tend to fall downward shows up in English in the early 17th century, but it was put in Aristotlean terms, which is to say, gravity is an example of objects returning to their "natural place" (which for massive objects is closer to the center of the Earth). Newton is the one who said, actually gravity is a force that not only explains that motion (the famous apple falling example) but also explains how planets rotate and everything else about the stars. Which is to say, Newton's accomplishment was hypothesizing a single force that explained a range of phenomena, and he called that force gravity. (Even this is an oversimplification — the term gravity was being used in a quasi-force like way by a few other people at the time.)

As for the language — in English it comes from Latin, initially just meaning "weighty" (Cf. "grave") but it is only the 17th century that it really starts to be applied in the way you are thinking, to the physical description.