Synonyms to pea brained

brainless, foolish, headless, ignorant, inept, insensate, irrational, lackbrained, lean-minded, lean-witted, mindless, not bright, of little brain, pin-brained, reasonless, senseless, slackminded, slackwitted, ungifted, unintellectual, unintelligent, unreasoning, untalented, unthinking, unwise, witless