From WordNet (r) 2.0 (August 2003) [wn]:
gaseous
adj : existing as or having characteristics of a gas; "steam is
water is the gaseous state" [ant: solid, liquid]
From The Collaborative International Dictionary of English v.0.48 [gcide]: Gaseous \Gas"e*ous\ (? or ?; 277), a. [From Gas. Cf. F. gazeux.] 1. In the form, or of the nature, of gas, or of an a["e]riform fluid. [1913 Webster] 2. Lacking substance or solidity; tenuous. "Unconnected, gaseous information." --Sir J. Stephen. [1913 Webster]