bust up verb 5bust-up noun 1forms 4 verb5 •(US, informal) To physically damage or ruin; to be ruined; to go bankrupt; to end (something).If I was school . . . I’d capitulate tomorrow. I’d bonfire the books, drain the inkwells and bust up the blackboard — if only he would stop hating. It’s wearing me out! — 1957 •(informal) To break up (end a relationship).I knew, because both Alison and Penny had taught me, that busting up with someone could be miserable, but I didn't know that getting off with someone could be miserable too. — 1995 •(slang) To express sudden and intense emotions; to burst into loud laughter. •(slang) To shoot (someone). •(Australia, slang) To spend money wildly, especially on alcoholic drinks. bust-up noun1 •(slang) An angry argument.“It was a real old bust-up. I do wish I knew what it was all about.” — 1920 formsbusted up · busting up · busts up · bust-ups