The Collaborative International Dictionary of English v.0.48:
Buoy \Buoy\, v. t. [imp. & p. p. Buoyed; p. pr. & vb. n.
1. To keep from sinking in a fluid, as in water or air; to
keep afloat; -- with up.
2. To support or sustain; to preserve from sinking into ruin
Those old prejudices, which buoy up the ponderous
mass of his nobility, wealth, and title. --Burke.
3. To fix buoys to; to mark by a buoy or by buoys; as, to
buoy an anchor; to buoy or buoy off a channel.
Not one rock near the surface was discovered which
was not buoyed by this floating weed. --Darwin.