1. filled with vapor

e.g. miasmic jungles
a vaporous bog

Synonym: miasmalmiasmicvapourous

2. resembling or characteristic of vapor

e.g. vaporous clouds

Synonym: vaporificvapourificvaporishvapourishvapourous

3. so thin as to transmit light

e.g. a hat with a diaphanous veil
filmy wings of a moth
gauzy clouds of dandelion down
gossamer cobwebs
sheer silk stockings
transparent chiffon
vaporous silks

Synonym: diaphanousfilmygauzygauze-likegossamersee-throughsheertransparentvapourouscobwebby