air [ME] The main modern sense of air, ‘the invisible gaseous substance surrounding the earth’ entered English via Old French and Latin from Greek aēr. Aerial [L16th], ‘existing or happening in the air’ then meaning ‘a rod or wire by which signals are transmitted or received’ [E20th], comes from the same source. Aerobic [L19th] is from aēr combined with Greek bios ‘live’. The senses of air as ‘an impression or manner’ and ‘a condescending manner’ (as in she gave herself airs) [E18th] are modelled on a French development which added ‘appearance’ to the meaning of the word. Airy-fairy [M19th] ‘impractical and foolishly idealistic’, was originally used to mean ‘delicate or light as a fairy’. The English poet Alfred, Lord Tennyson (1809–1892), in his poem ‘Lilian’ (1830), described the subject as ‘Airy, fairy Lilian, Flitting, fairy Lilian’.