- a boat or some other floating structure used as one of the supports for a temporary bridge over a river.
- a float for a derrick, landing stage, etc.
- a float for raising a sunken or deeply laden vessel in the water; a camel or caisson.
- a seaplane float.
- the card game twenty-one.
- a watertight float or vessel used where buoyancy is required in water, as in supporting a bridge, in salvage work, or where a temporary or mobile structure is required in military operations
- (as modifier)
- a float, often inflatable, for raising a vessel in the water
- a gambling game in which players try to obtain card combinations worth 21 points
- (in this game) the combination of an ace with a ten or court card when dealt to a player as his first two cards
