A flexible bag designed to be inflated with hot air or with a gas, such as helium, that is lighter than the surrounding air, causing it to rise and float in the atmosphere.
Such a bag with sufficient capacity to lift and transport a suspended gondola or other load.
Such a bag shaped like a figure or object when inflated; an inflatable.
A usually round or oblong inflatable rubber bag used as a toy.
Medicine A sac that is inserted into a body cavity or tube and distended with air or gas for therapeutic purposes, such as angioplasty.
A rounded or irregularly shaped outline containing the words that a character in a cartoon is represented to be saying.
v.
bal·looned, bal·loon·ing, bal·loons
v.
intr.
To ascend or ride in a balloon.
To expand or swell out like a balloon. See Synonyms at bulge.
To increase or rise quickly.
v.
tr. To cause to expand by or as if by inflating. adj. Suggestive of a balloon, as in shape: balloon curtains.
[French ballon, from Italian dialectal ballone, augmentative of balla, ball, of Germanic origin; see bhel-2 in Indo-European roots.] bal·loon'ist n.
[buh-loo-nist] 
nɪst