bum

bum · noun, verb, interjection¹

1. Middle English · inherited frombom
2. English todaybum

Attested since the 1300s, as Middle English bom (found in John Trevisa's 1387 Translation of the 'Polychronicon' of Ranulph Higden, "his bom is oute"), of uncertain origin. Sometimes suggested to be a shortening of botme, botom, bottum (“bottom”), but this is contradicted by the fact that bottom is not attested in reference to the buttocks until the late 1700s. Suggested by some old and modern references to be onomatopoeic. Compare also Old Irish, Scottish Gaelic bun (“base, bottom”). The anal sex senses (noun and verb), as well as the adjective (esp. the first) sense, are expletive-avoiding (i.e. Bowdlerized) shortenings of bumfuck.

bum · noun, verb, adjective²

1. German · derived fromBummler“loafer”
2. English todaybum

1864, back-formation from bummer, from German Bummler (“loafer”), from bummeln (“to loaf”).

bum · verb³

Back-formation from bum out.

bum · noun, verb⁴

See boom.

bum · noun⁵

Abbreviation.