apish, arrested, asinine, babbling, backward, batty, befooled, beguiled, besotted, blithering, brainless, buffoonish, burbling, cockeyed, crackbrained, cracked, crazy, credulous, cretinistic, cretinous, daffy, daft, dazed, dim-witted, dithering, dizzy, doting, driveling, drooling, dull, dumb, fatuitous, fatuous, feebleminded, flaky, fond, fool, foolheaded, foolish, fuddled, futile, gaga, goofy, gulled, half-baked, half-witted, idiotic, imbecile, imbecilic, inane, inept, infatuated, insane, kooky, loony, mad, maudlin, maundering, mentally defective, mentally deficient, mentally handicapped, mentally retarded, mongoloid, not all there, nutty, retarded, sappy, screwy, senseless, sentimental, silly, simple, simpleminded, simpletonian, slobbering, slow-witted, stupid, subnormal, thoughtless, wacky, wet, witless