n. 1. a. 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. b. Such a bag with sufficient capacity to lift and transport a suspended gondola or other load. c. Such a bag shaped like a figure or object when inflated; an inflatable. 2. A usually round or oblong inflatable rubber bag used as a toy or decoration. 3. Medicine An inflatable device that is inserted into a body cavity or structure and distended with air or gas for therapeutic purposes, such as angioplasty. 4. a. See speech bubble. b. See thought bubble. 5. A balloon payment. v. bal·looned, bal·loon·ing, bal·loons v.intr. 1. To ascend or ride in a balloon. 2. To expand or swell out like a balloon. See Synonyms at bulge. 3. To increase or rise quickly: expenses ballooning out of control. v.tr. To cause to expand by or as if by inflating: unforeseen expenditures that ballooned the deficit. 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 the Appendix of Indo-European roots.] bal·loonist n. |
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