Wikipedia coyly suggests that some notions and views kept circulating (apparently since Adam and Eve) until finally Kepler, of all people, ... etc. I find this hard to believe. Please elucidate.
Searching for the definition in dictionary.com you can find this under the word origin and history section:
Late 14c., "the eye socket," from Old French orbite or directly from Medieval Latin orbita, transferred use of Latin orbita "wheel track, beaten path, rut, course, orbit Astronomical sense first recorded 1690s in English; it was in classical Latin, revived in Gerard of Cremona's translation of Avicenna.
I believe that this is what you are looking for.
The word orbit could refer to three latin words : orbis, which means "ring", orbitus, which describes et circular shape, and orbita, which describes the track of a wheel.
As you can see, the meanings of this word are quite old. It is therefore hard to tell the first time it was used to describe a celestial body's round trajectory. But the word itself comes from latin.