a (usually rigid) buoyant ring or other device used to support the body in water; = buoy, n. 1b.

A floating appliance for supporting something in the water. In various other applications (see quots.).

Each of a pair of inflatable floats worn on the upper arms of a person learning to swim, to give increased buoyancy. Cf. armband, n. 3.

(a) a loop of rubber used to secure or seal something; (b) an inflatable ring of rubber or similar material used as a flotation device.