From Middle English *quacken, queken (âto croak like a frog; make a noise like a duck, goose, or quailâ), from quack, qwacke, quek, queke (âquackâ, interjection and noun), also kek, keke, whec-, partly of imitative origin and partly from Middle Dutch quacken (âto croak, quackâ), from Old Dutch *kwaken (âto croak, quackâ), from Proto-Germanic *kwakanÄ, *kwakÅnÄ (âto croakâ), of imitative origin.