rimming (Noun) — Sexual oral stimulation of the anus.
rimming (Verb) — Run around the rim of. ex. "Sugar rimmed the dessert plate"
rimming (Verb) — Furnish with a rim. ex. "rim a hat"
rimming (Verb) — Roll around the rim of. ex. "the ball rimmed the basket"
rimming (Verb) — (informal) perform anilingus - sexually stimulate the anus with the mouth or tongue.