What is another word for "subtile"?

Roget's Thesaurus (1911) lists these synonyms for "subtile": absence, air, airy, astatic, balloon, barm, bubble, buoy, buoyancy, buoyant, cavernous, cobweb, compressibility, compressible, convection, cork, diffusion, dilatation, dilate, down, draft, dust, ether, ethereal, evaporation, expand, expansion, feather, ferment, fine, flimsy, float, floating, flue, gas, gossamer, gossamery, helium, hollow, hot.