UK, 1941—a fighter pilot in the Royal Air Force; also used by the military land forces of any member of the R.A.F.—originally referred to WWII advertisements for Brylcreem hair cream, featuring a fighter pilot
UK—an ambulance (i.e., a vehicle designed to carry sick or injured people)—originally (Royal Air Force slang, 1921): a specially equipped airplane for carrying sick or injured people
a married woman living apart from her husband (18th century)—originally (16th century) an unmarried woman who has borne an illegitimate child—alludes to a bed of grass as a typical place for illicit sexual intercourse
UK—anything which discourages or inhibits sexual activity—originally (1943, British military slang): the sturdy, practical and unattractive underwear issued to female service personnel
to intimidate somebody—UK, from 1958 onwards in books by Frank Norman (1930-1980)—also, the noun ‘frightener’ designates a member of a criminal gang who intimidates the victims of its activities
a person who seems eager to take on difficult or unpleasant tasks—UK, 1829—originally, in pugilistic slang, a fighter who “takes a deal of punishment before he is satisfied”
expresses indignation, disbelief or amazement—USA, 1818—expanded form of the exclamation ‘ye gods’—perhaps a reference to the miracle of the loaves and fishes fed to the five thousand in the gospel of Matthew