brainless

from WordNet (r) 3.0 (2006)

brainless
    adj 1: not using intelligence [syn: {brainless}, {headless}]

from The Collaborative International Dictionary of English v.0.48

Brainless \Brain"less\, a.
   Without understanding; silly; thoughtless; witless. --
   {Brain"less*ness}, n.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

93 Moby Thesaurus words for "brainless":
      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, giddy-brained,
      giddy-headed, giddy-pated, giddy-witted, 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