Loontoonious Posted in L Best definition Loontoonious To act like a crazy cartoon Character. Examples: Donald Duck, Daffy Duck, Bugs Bunny, etc. To say things so off the wall they are Loontoonious. “Did you here Mike last night, He was just loontoonious How satisfied are you with the definition? Looking for Loontoonious meaning? Delighted that you discovered the greatest determine on our web site! Recently this definition was actually observed 5 times.