1690s, "sculpture of upper torso and head," from French buste (16c.), from Italian busto "upper body," from Latin bustum "funeral monument, tomb," originally "funeral pyre, place where corpses are burned," perhaps shortened from ambustum, neuter of ambustus "burned around," past participle of amburere "burn around, scorch," from ambi- "around" + urere "to burn." Or perhaps from Old Latin boro, the early form of classical Latin uro "to burn." Sense development in Italian is probably from Etruscan custom of keeping dead person's ashes in an urn shaped like the person when alive. Meaning "bosom" is by 1884.
variant of burst (n.), 1764, American English. For loss of -r-, cf. ass (n.2). Originally "frolic, spree;" sense of "sudden failure" is from 1842. Meaning "police raid or arrest" is from 1938. Phrase ______ or bust as an emphatic expression attested by 1851 in British depictions of Western U.S. dialect. Probably from earlier expression bust (one's) boiler, by late 1840s, a reference to steamboat boilers exploding when driven too hard.
"to burst," 1806, variant of burst (v.); for loss of -r-, cf. ass (n.2). Meaning "go bankrupt" is from 1834. Meaning "break into" is from 1859. The slang meaning "demote" (especially in a military sense) is from 1918; that of "place under arrest" is from 1953 (earlier "to raid" from Prohibition). In card games, "to go over a score of 21," from 1939. Related: Busted; busting.
(Variations: break may replace bust; balls or buns or butt or chops or conk or hump or nuts or stones or sweet ass or tail may replace ass) To work or perform to one's utmost; exert oneself mightily: Yeah but, what if he busts his ass, goes to a lot of trouble/ If They Break Their Asses They Might Get into College Program/ I'm finished busting my hump on that kind of work/ I busted my butt to get those business people to sponsor me/ We're really busting our buns/ Here I was, busting my tail to develop young players ( first form 1940s+)