1) Aery 2) Airlike 3) Ethereal 4) Gaseous 5) Insubstantial 6) Unsubstantial 1) Airlike 2) Gaseous 3) Light as gases 4) Unreal 5) Unsubstantial 
of the form or shape of gas; gaseous
• (a.) Having the form or nature of air, or of an elastic fluid; gaseous. Hence fig.: Unreal.
A'ër·i·form adjective [ Latin aër air + -form : confer French aériforme .] Having the form or nature of air, or of an elastic fluid; gaseous. Hence fig.: Unreal. 
[adj] - resembling air or having the form of air 2. [adj] - characterized by lightness and insubstantiality
aerial adjective characterized by lightness and insubstantiality; as impalpable or intangible as air; `figures light and aeriform come unlooked for and melt away`- Thomas Carlyle; `aerial fancies`; `an airy apparition`; `physical rather than ethereal form...
having the form or nature of air; gaseous. · unsubstantial; unreal.