• plural noun female breasts. The only slang word for the breasts which is currently acceptable in ‘polite circles’. (It is also used in the singular form, ‘boob’.) It is a less brusque variant of the more vulgar bubs or bubbies which probably derive from the noises made by suckling babies. Boobs has been a fashionable term since the mid-1960s; bubbie since the 17th century.