hmm, the online dictionary says it's just fine...
Etymology: Buoy \Buoy\, noun. [D. boei buoy, fetter, from Old French boie, buie, chain, fetter, French bou['e]e a buoy, from Latin boia. ``Boiae genus vinculorum tam ferreae quam ligneae.'' --Festus. So called because chained to its place.]. (references)
bu⋅oy
/ˈbui, bɔɪ/ Show Spelled Pronunciation [boo-ee, boi] Show IPA Pronunciation
–noun
1. Nautical. a distinctively shaped and marked float, sometimes carrying a signal or signals, anchored to mark a channel, anchorage, navigational hazard, etc., or to provide a mooring place away from the shore.
2. a life buoy.
–verb (used with object)
3. to keep afloat or support by or as if by a life buoy; keep from sinking (often fol. by up): The life jacket buoyed her up until help arrived.
4. Nautical. to mark with a buoy or buoys.
5. to sustain or encourage (often fol. by up): Her courage was buoyed by the doctor's assurances.
–verb (used without object)
6. to float or rise by reason of lightness.