subtility†; subtilty†, subtlety; sponginess, compressibility. rarefaction, expansion, dilatation, inflation, subtilization†. vaporization, evaporation, diffusion, gassification†. ether &c (gas) 334. V. rarefy, expand, dilate, subtilize†. Adj. rare, subtile, thin, fine, tenuous, compressible, flimsy, slight; light &c 320; cavernous, spongy &c (hollow) 252. rarefied &c v.; unsubstantial; uncompact†, incompressed†; rarefiable†.