Rarefy

v. t.	1.	To make rare, thin, porous, or less dense; to expand or enlarge without adding any new portion of matter to; - opposed to condense. [imp. & p. p. Rarefied (răr"ė*fīd); p. pr. & vb. n. Rarefying (răr"ė*fī`ĭng).]
v. i.	1.	To become less dense; to become thin and porous.

Verb	1.	rarefy - lessen the density or solidity of; "The bones are rarefied"
	2.	rarefy - make more subtle or refined Synonyms: sublimate, subtilize
	3.	rarefy - weaken the consistency of (a chemical substance) Synonyms: attenuate

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