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.

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