horse feather

want of intelligence, want of intellect [more]; shadowness, silliness, foolishness; imbecility, incapacity, vacancy of mind, poverty of intellect, clouded perception, poor head, apartments to let; stupidity, stolidity; hebetude, dull understanding, meanest capacity, shortsightedness; incompetence (unskillfulness)., one's weak side; bias; infatuation (insanity)., simplicity, puerility, babyhood; dotage, anility, second childishness, fatuity; idiocy, idiotism; driveling., folly, frivolity, irrationality, trifling, ineptitude, nugacity, inconsistency, lip wisdom, conceit; sophistry; giddiness (inattention); eccentricity; extravagance (absurdity); rashness., act of folly., be imbecile; have no brains, have no sense [more]., trifle, drivel, radoter, dote; ramble (madness); play the fool, play the monkey; take leave of one's senses; not see an inch beyond one's nose; stultify oneself; talk nonsense.

[Applied to persons] unintelligent, unintellectual, unreasoning; mindless, witless, reasoningless, brainless; halfbaked; having no head; not bright; inapprehensible., weak headed, addle headed, puzzle headed, blunder headed, muddle headed, muddy headed, pig headed, beetle headed, buffle headed, chuckle headed, mutton headed, maggoty headed, grossheaded; beef headed, fat witted, fat-headed., weak-minded, feeble-minded; dull minded, shallow minded, lack-brained; rattle-brained, rattle headed; half witted, lean witted, short witted, dull witted, blund-witted, shallow-pated, clod-pated, addle-pated; dim-sighted, short-sighted; thick-skulled; weak in the upper story., shallow, borne, weak, wanting, soft, sappy, spoony; dull, dull as a beetle; stupid, heavy, insulse, obtuse, blunt, stolid, doltish; asinine; inapt; prosaic; hebetudinous., childish; infantine, infantile, babyish, babish; puerile, anile; simple (credulous)., fatuous, idiotic, imbecile, driveling; blatant, babbling; vacant; sottish; bewildered., blockish, unteachable, Boeotian, Boeotic; bovine; ungifted, undiscerning, unenlightened, unwise, unphilosphical; apish; simious., foolish, silly, senseless, irrational, insensate, nonsensical, inept; maudlin.