Buoy

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.
a life buoy.
to keep afloat or support by or as if by a life buoy; keep from sinking (often followed by up):
The life jacket buoyed her up until help arrived.
Nautical. to mark with a buoy or buoys.
to sustain or encourage (often followed by up):
Her courage was buoyed by the doctor’s assurances.
to float or rise by reason of lightness.
Contemporary Examples

Inside Seal Team Six by Don Mann Excerpt Don Mann December 3, 2011
Daily Beast Contributors Weigh In on Obama’s 2012 State of the Union Address January 24, 2012
10 Touching Tributes from the Kennedy Services The Daily Beast Video August 28, 2009
Karen Russell: How I Write Noah Charney February 5, 2013
How Virginia Democrats Are Winning on Gun Safety Eleanor Clift October 29, 2013

Historical Examples

Witches Cove Roy J. Snell
Luttrell Of Arran Charles James Lever
The Memories of Fifty Years William H. Sparks
The Three Commanders W.H.G. Kingston
Wyndham’s Pal Harold Bindloss

noun
a distinctively shaped and coloured float, anchored to the bottom, for designating moorings, navigable channels, or obstructions in a body of water See also life buoy
verb
(transitive) usually foll by up. to prevent from sinking: the belt buoyed him up
(transitive) usually foll by up. to raise the spirits of; hearten
(transitive) (nautical) to mark (a channel or obstruction) with a buoy or buoys
(intransitive) to rise to the surface
n.
v.