American English, early 20th century—primarily used of a present that delivers repeated enjoyment in the course of time—also sarcastically used of a person or situation constituting a recurring problem
indoor football—UK, public-school & university slang, 1897—‘fug’: a thick, close, stuffy atmosphere, especially that of a room overcrowded and with little or no ventilation
UK, 1809—the level of physical force deemed appropriate or justifiable by law in protecting oneself or one’s family or property; also: in apprehending a criminal suspect or preventing a crime
‘air guitar’: an imaginary guitar played by miming, especially to rock music—‘air band’: a pretend rock band whose members mime the action of playing imaginary instruments—USA, 1978