| Rarefy 1. (v. t.) To make rare, thin, or less dense; to expand or enlarge without adding any new matter; -- opposed to condense. 2. (v. i.) To become less dense; to become thin and porous. Thesaurus Entries add to, adulterate, aggrandize, amplify, attenuate, augment, baptize, bloat, blow up, broaden, build, build up, bulk, bulk out, crescendo, cut, dematerialize, develop, dilate, dilute, disembody, distend, emacerate, emaciate, enervate, enlarge, etherealize, expand, extend, hike, hike up, huff, increase, inflate, irrigate, magnify, puff, puff up, pump, pump up, raise, reduce, sap, spiritualize, stretch, subtilize, sufflate, swell, thin, thin away, thin down, thin out, up, water, water down, weaken, widen |