arrested, babbling, backward, blithering, burbling, crackbrained, cracked, crazy, cretinistic, cretinous, dithering, driveling, drooling, half-baked, half-witted, idiotic, imbecile, imbecilic, maundering, mentally defective, mentally deficient, mentally handicapped, mentally retarded, moronic, not all there, retarded, simple, simpleminded, simpletonian, slobbering, subnormal