boob [E20th] Boob meaning ‘mistake’ is an abbreviation of booby ‘stupid or childish person’ in use two centuries earlier and probably derived from Spanish bobo, from Latin balbus ‘stammering’. Boo-boo which arose in the 1930s in the US for ‘mistake’ is from boob, as is the slang term boob tube [M20th] for a television. Also American is boob for ‘breast’. This is an abbreviation of another booby, a 1930s alteration of dialect booby [M20th] and bubby [M17th], which was probably originally a children’s word, perhaps from the sound of sucking. The boob tube that is a garment came from this sense in the 1970s.