wackadoodleEnglishOxford Dictionary of Englishwackadoodle /ˈwakəduːdl / (also whackadoodle) US English informal, derogatory ▸ noun an eccentric or fanatical person: an alarming number of wackadoodles predict the world will indeed end. ▸ adjective eccentric or fanatical: he has given credence to a lot of wackadoodle beliefs. – ORIGIN 1990s: from wackadoo.