[buh-loon] 
| 1. | a bag made of thin rubber or other light material, usually brightly colored, inflated with air or with some lighter-than-air gas and used as a children's plaything or as a decoration. |
| 2. | a bag made of a light material, as silk or plastic, filled with heated air or a gas lighter than air, designed to rise and float in the atmosphere and often having a car or gondola attached below for carrying passengers or scientific instruments. |
| 3. | (in drawings, cartoons, etc.) a balloon-shaped outline enclosing words represented as issuing from the mouth of the speaker. |
| 4. | an ornamental ball at the top of a pillar, pier, or the like. |
| 5. | a large, globular wineglass. |
| 6. | Chemistry Now Rare. a round-bottomed flask. |
| 7. | to go up or ride in a balloon. |
| 8. | to swell or puff out like a balloon. |
| 9. | to multiply or increase at a rapid rate: Membership has ballooned beyond all expectations. |
| 10. | to fill with air; inflate or distend (something) like a balloon. |
| 11. | puffed out like a balloon: balloon sleeves. |
| 12. | Finance. (of a loan, mortgage, or the like) having a payment at the end of the term that is much bigger than previous ones. |
balloon bal·loon (bə-l&oomacr;n')
n.
An inflatable spherical device that is inserted into a body cavity or structure and distended with air or gas for therapeutic purposes.