- Possibly from bug-a-boo, an imaginary evil goblin.
- Possibly from bubo, a swollen lymph node especially obvious in sufferers of bubonic plague.
- Possibly from the sound a baby or young toddler might make.
- Possibly borrowing from French bobo (“boo-boo”)
- (countable, colloquial, often childish) A mistake or error.
- (countable, colloquial, childish, by or to young children) A minor injury, such as a cut or a bruise.
- (uncountable, colloquial, childish, by or to young children) Feces.
- (error): blooper, blunder, faux pas, fluff, gaffe, lapse, slip, stumble, thinko
- (minor injury): owie, scrape, bruise, nick, scratch
- (void one’s bowels): (slang) crap, (obsolete) drite, (slang) dump, (informal) pinch a loaf, (informal, humorous) drop a bomb, (informal, humorous) drop the kids off at the pool, (vulgar) shit, (vulgar) shite, (vulgar) take a shit, (slang) take a dump, (informal) drop a deuce
Sometimes used sarcastically when the speaker believes the listener is overreacting to a very minor injury, as in Aw, did the little boy get a boo-boo?