unsound

1 having or showing a very abnormal or sick state of mind disgruntled relatives tried to prove that the woman was of unsound mind when she made her will Synonyms balmy, barmy [chiefly British], bats, batty, bedlam, bonkers, brainsick, bughouse [slang], certifiable, crackbrained, cracked, crackers, crackpot, cranky [dialect], crazed, crazy, cuckoo, daffy, daft, demented, deranged, fruity [slang], gaga, haywire, kooky (also kookie), loco [slang], loony (also looney), loony tunes (or looney tunes), lunatic, mad, maniacal (also maniac), mental, meshuga (or meshugge also meshugah or meshuggah), moonstruck, non compos mentis, nuts, nutty, psycho, psychotic, scatty [chiefly British], screwy, unbalanced, unhinged, insane, wacko (also whacko), wacky (also whacky), wud [chiefly Scottish]Related Words dotty, fey, loopy, off, potty [chiefly British], teched (or tetched), touched; aberrant, delirious, delusional, delusionary, disordered, disturbed, neurotic, obsessive-compulsive, paranoiac (also paranoic), paranoid (also paranoidal), schizoid, schizophrenic, sociopathic; eccentric, odd, oddball, pixilated (also pixillated), queer, strange; foolish, senseless, witless; irrational, unreasonable; amok (or amuck), ape, ballistic, bananas, berserk, nuclear; depressed; distracted, distraught, frantic, frenzied, haywire, hysterical (also hysteric), raving, wigged-out; fixated, monomaniac, monomaniacal, obsessedNear Antonyms clear, lucid, rational, reasonable; judicious, sensible, wise; healthy, normal, well-adjusted; unneuroticAntonyms balanced, compos mentis, sane, sound, uncrazy

2 not being in agreement with what is true an unsound and pernicious stereotype Synonyms erroneous, inaccurate, incorrect, inexact, invalid, off, false, untrue, untruthful, wrongRelated Words counterfactual; specious, spurious; deceptive, delusive, delusory, distorted, fallacious, fictitious, illusory, misleading; amiss, askew, awry; deceitful, dishonest, fraudulent, lying, mendacious; unconfirmed, unproven, untested; fabricated, invented, made-up, trumped-upNear Antonyms confirmed, demonstrated, established, proven, tested; faultless, flawless, impeccable, letter-perfect, perfectAntonyms accurate, correct, errorless, exact, factual, precise, proper, right, sound, true, valid, veracious

3 not using or following good reasoning it is clearly unsound to argue that just because a scientific explanation for that phenomenon does not currently exist, no such explanation is possible Synonyms fallacious, illegitimate, inconsequent, inconsequential, invalid, irrational, nonrational, unreasonable, unreasoning, illogical, weakRelated Words eristic (also eristical), misleading, sophistic (or sophistical), specious; half-baked, ill-advised, misguided, unconsidered, unreasoned; inconsistent; absurd, asinine, foolish, meaningless, nonsensical, preposterous, reasonless, senseless, silly; Kafkaesque, odd, peculiar, strange, surreal, unusual, weird; insane, mad, nutty, wacky (also whacky); disordered, disorganized, rambling, random; unconvincing; inexplicable, unaccountable, unexplainableNear Antonyms commonsense, sane, sensible, sober, wise; enlightened, informed, just, justified, reasoned; ordered, organized; clear, cogent, compelling, convincing, credible, persuasive, plausible, satisfying, solid; certain, sure, true; confirmed, corroborated, demonstrated, established, substantiated, validatedAntonyms logical, rational, reasonable, sound, valid, well-founded, well-grounded

4 temporarily suffering from a disorder of the body an unsound horse that will have to be disqualified from the race Synonyms ailing, bad, down, ill, indisposed, peaked, peaky, poorly, punk, run-down, sickened, unhealthy, sick, unwellRelated Words symptomatic; cruddy, lousy, seedy, sickish; nauseated, nauseous, qualmish, queasy (also queazy), squeamish; airsick, carsick, seasick; dizzy, light-headed, shaky, woozy; achy, feverish; diseased, disordered; decrepit, feeble, fragile, frail, infirm, invalid, sickly, weak, weakly; afflicted, troubled; challenged, debilitated, disabled, halt, incapacitated, lame; hypochondriac, hypochondriacalNear Antonyms able-bodied, conditioned, fit, well-conditioned; cured; better, convalescing, improved, mending, recovering, recuperating, rehabilitated; hardy, hearty, lusty, robust, rugged, stalwart, strong, tough; blooming, bouncing, chipper, flourishing, flush, thrivingAntonyms hale, healthful, healthy, sound, well, whole, wholesome