felicitous

The adjective felicitous has been a part of our language since the late 18th century, but felicity, the noun meaning "great happiness," and later, "aptness," was around even in Middle English (as felicite, a borrowing from Anglo-French). Both words ultimately derive from the Latin adjective felix, meaning "fruitful" or "happy." The connection between happy and felicitous continues today in that both words can mean "notably fitting, effective, or well adapted." Happy typically suggests what is effectively or successfully appropriate (as in "a happy choice of words"), and felicitous often implies an aptness that is opportune, telling, or graceful (as in "a felicitous phrase").