Old English dōm 'statute, judgement', of Germanic origin, from a base meaning 'to put in place'; related to do¹.

• The ancient root of doom meant ‘to put in place’ and is also the root of do (Old English). By the time that written English records began the emphasis had narrowed to putting law and order in place: the Old English senses of doom include ‘a law, statute’, ‘a judicial decision’, and ‘the right to judge’. In the context of the end of the world, the word ‘judgement’ was not used until the 16th century—before that the usual term for Judgement Day was doomsday (source of the name the Domesday Book for the survey of the land ordered by William the Conqueror in 1085 for tax purposes, because it was the final authority on such things). In the Middle Ages this was also shortened to doom, a use that survives only in the crack of doom. ‘ We're doomed!’ was the catchphrase of the gloomy Scottish undertaker Frazer, played by John Laurie, in the BBC TV comedy Dad's Army (1968–77). The 1947 musical Finian's Rainbow popularized gloom and doom, which became a catchphrase when it was made into a film in 1968. The idea seemed appropriate to a world threatened by nuclear war.