WordNet sense 1 (so thin as to transmit light):

cobwebby, diaphanous, filmy, gauzy, gossamer, see-through, sheer, transparent, gauze-like, vapourous

WordNet sense 2 (of relatively small extent from one surface to the opposite or in cross section):

thin

WordNet sense 3 (resembling or characteristic of vapor):

vaporific, vaporish, vapourish, vapourific

WordNet sense 4 (existing as or having characteristics of a gas):

gaseous

WordNet sense 5 (filled with vapor):

miasmic, miasmal

WordNet sense 6 (full of or covered with clouds):

cloudy