bu·oy / ˈboō-ē; boi/ • n. an anchored float serving as a navigation mark, to show reefs or other hazards, or for mooring.• v. [tr.] 1. keep (someone or something) afloat: I let the water buoy up my weight. ∎  (often be buoyed) cause to become cheerful or confident: the party was buoyed by an election victory. ∎  (often be buoyed) cause (a price) to rise to or remain at a high level: the price is buoyed up by investors.2. mark with a buoy: [as adj.] (buoyed) a buoyed channel.

buoy XIII. Earlier forms boy(e), buy, buie, bwoy; prob. — MDu. bo(e)ye (Du. boei), perh. — OF. boie, buie chain, fetter :- L. boia, esp. pl. boiæ — Gr. boeîai (sc. doraí) straps of ox-leather, f. boús (see COW1).