wackadoodleEnglishOxford New American Dictionarywackadoodle /ˈwakəˌdo͞odl, ˈwækəˌdudl / (also whackadoodle) US informal ▸ 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.