balloon

1 to become greater in extent, volume, amount, or number the number of students who stay home sick balloons every winter Synonyms accelerate, accumulate, appreciate, increase, boom, build up, burgeon (also bourgeon), climb, enlarge, escalate, expand, gain, mount, multiply, mushroom, proliferate, rise, roll up, snowball, spread, swell, waxRelated Words jump, rocket, skyrocket, surge; heighten, intensify, redouble; blow up, bulk, distend, inflate, puff (up); crescendo, crest, peakAntonyms contract, decrease, diminish, dwindle, lessen, recede, wane

2 to extend outward beyond a usual point the paper bag ballooned and blew away as the wind lifted it skyward Synonyms bag, bulge, beetle, belly, billow, bunch, jut, overhang, poke, pooch [chiefly dialect], pouch, pout, project, protrude, stand out, start, stick out, swellRelated Words dome; blow up, inflate; dilate, distend, expand; mushroom, snowball; elongate, extend, lengthen, stretchNear Antonyms compress, condense, constrict, contract, shrink