apish, asinine, batty, befooled, beguiled, besotted, buffoonish, cockeyed, crazy, credulous, daffy, daft, dazed, dizzy, doting, dumb, empty-headed, fatuitous, fatuous, featherbrained, featherheaded, flaky, fluttery, fond, fool, foolheaded, foolish, frivolous, fuddled, futile, gaga, giddy-brained, giddy-headed, giddy-pated, giddy-witted, giddy, goofy, gulled, harebrain, harebrained, headless, idiotic, ignorant, imbecile, inane, inept, infatuated, insane, insensate, irrational, kooky, lackbrained, lean-minded, lean-witted, loony, mad, maudlin, mindless, moronic, nitwitted, not bright, nutty, of little brain, pea-brained, pin-brained, rattlebrained, rattleheaded, rattlepated, reasonless, sappy, scatterbrained, scramblebrained, screwy, senseless, sentimental, shatterbrained, silly, slackminded, slackwitted, stupid, thoughtless, ungifted, unintellectual, unintelligent, unreasoning, untalented, unthinking, unwise, unwitty, wacky, weak-minded, wet, witless