buoy

Concise Oxford English Dictionary © 2008 Oxford University Press:
buoy /bɔɪ/

▶noun an anchored float serving as a navigation mark, to show hazards, or for mooring. ▶verb

• 1 (usu. be buoyed up) keep afloat.

  ■ cause (a price) to rise to or remain high.

• 2 mark with a buoy.

– derivatives
buoyage noun.

– origin ME: prob. from MDu. boye, boeie, from a Gmc base meaning ‘signal’.