Roget's Thesaurus

#322. Rarity

Nouns

rarity, tenuity; absence of solidity etc. 321; subtility; subtilty, subtlety; sponginess, compressibility. rarefaction, expansion, dilatation, inflation, subtilization. vaporization, evaporation, diffusion, gassification. ether etc. (gas) 334.

Verbs

rarefy, expand, dilate, subtilize.

Adjectives

rare, subtile, thin, fine, tenuous, compressible, flimsy, slight; light etc. 320; cavernous, spongy etc. (hollow) 252. rarefied etc. v.; unsubstantial; uncompact, incompressed; rarefiable.