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.

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.

(in drawings, cartoons, etc.) a balloon-shaped outline enclosing words represented as issuing from the mouth of the speaker.

an ornamental ball at the top of a pillar, pier, or the like.

a large, globular wineglass.

Chemistry Now Rare . a round-bottomed flask.

to go up or ride in a balloon.

to swell or puff out like a balloon.

to multiply or increase at a rapid rate

Membership has ballooned beyond all expectations.

to fill with air; inflate or distend (something) like a balloon.

puffed out like a balloon

balloon sleeves.

Finance . (of a loan, mortgage, or the like) having a payment at the end of the term that is much bigger than previous ones.

noun

airship , bladder , blimp , dirigible , zeppelin

verb

belly , blow up , bulge , dilate , distend , enlarge , expand , inflate , puff out , swell , bag , beetle , jut , overhang , pouch , project , protrude , protuberate , stand out , stick out , airship , billow , blimp , gasbag , zeppelin