lackbrain

CIDE DICTIONARY

lackbrain, n. 

 One who is deficient in understanding; a witless person.  Shak.  [1913 Webster]

ROGET THESAURUS

lackbrain

Fool

N fool, idiot, tomfool, wiseacre, simpleton, witling, dizzard, donkey, ass, ninny, ninnyhammer, chowderhead, chucklehead, dolt, booby, Tom Noddy, looby, hoddy-doddy, noddy, nonny, noodle, nizy, owl, goose, goosecap, imbecile, gaby, radoteur, nincompoop, badaud, zany, trifler, babbler, pretty fellow, natural, niais, child, baby, infant, innocent, milksop, sop, oaf, lout, loon, lown, dullard, doodle, calf, colt, buzzard, block, put, stick, stock, numps, tony, bull head, dunderhead, addlehead, blockhead, dullhead, loggerhead, jolthead, jolterhead, beetlehead, beetlebrain, grosshead, muttonhead, noodlehead, giddyhead, numbskull, thickskull, lackbrain, shallowbrain, dimwit, halfwit, lackwit, dunderpate, lunkhead sawney, gowk, clod, clod-hopper, clod-poll, clot-poll, clot-pate, bull calf, gawk, Gothamite, lummox, rube, men of Boeotia, wise men of Gotham, un sot a triple etage, sot, jobbernowl, changeling, mooncalf, gobemouche, dotard, driveler, old fogey, old woman, crock, crone, grandmother, cotquean, henhussy, incompetent (insanity), greenhorn, dunce, lubber, madman, one who will not set the Thames on fire, one who did not invent gunpowder, qui n'a pas invente' la poudre, no conjuror, fortuna favet fatuis, les fous font les festinas et les sages les mangen, nomina stultorum parietibus harrent, stultorum plena sunt omnia.