1630s, from Mod.L. atmosphaera, from atmo-, comb. form of Gk. atmos "vapor, steam" + spharia "sphere." First used in Eng. in connection with the Moon, which, as it turns out, doesn't have one. Figurative sense of "surrounding influence, mental or moral environment" is 1797. Gk. atmos is from PIE *awet-mo-, from base *wet- "to blow, inspire, spiritually arouse" (see wood (adj.)).