Not suitable or right or appropriate.

Roget 568: ungrammatical; incorrect, inaccurate; faulty; improper, incongruous; solecistic, solecistical^†.   

Roget 647: inexpedient, undesirable; unadvisable, inadvisable; objectionable; inapt, ineligible, inadmissible, inconvenient; incommodious, discommodious^†; disadvantageous; inappropriate, unfit etc. (inconsonant) 24.    ill-contrived, ill-advised; unsatisfactory; unprofitable &c.; unsubservient etc. (useless) 645; inopportune etc. (unseasonable) 135; out of place, in the wrong place; improper, unseemly.    clumsy, awkward; cumbrous, cumbersome; lumbering, unwieldy, hulky^†; unmanageable etc. (impracticable) 704; impedient etc. (in the way) 706^†.    unnecessary etc. (redundant) 641.    ... show more

Roget 499: unintelligent [Applied to persons], unintellectual, unreasoning; mindless, witless, reasoningless^†, brainless; halfbaked; having no head etc. 498; not bright etc. 498; 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, blunt-witted, shallow-pated^†, clod-pated^†, addle-pated^†, addle-brained^†; 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 etc. 699; prosaic etc. 843; hebetudinous^†.    childish, child-like; infantine^†, infantile, babyish, babish^†; puerile, anile; simple etc. (credulous) 486; old-womanish.    fatuous, idiotic, imbecile, driveling; blatant, babbling; vacant; sottish; bewildered etc. 475.    blockish^†, unteachable Boeotian, Boeotic; bovine; ungifted, undiscerning^†, unenlightened, unwise, unphilosophical^†; apish; simious^†.    foolish, silly, senseless, irrational, insensate, nonsensical, inept; maudlin.    narrow-minded etc. 481; bigoted etc. (obstinate) 606; giddy etc. (thoughtless) 458; rash etc. 863; eccentric etc. (crazed) 503.    [Applied to actions] foolish, unwise, injudicious, improper, unreasonable, without reason, ridiculous, absurd, idiotic, silly, stupid, asinine; ill-imagined, ill-advised, ill-judged, ill-devised; mal entendu [Fr.]; inconsistent, irrational, unphilosophical^†; extravagant etc. (nonsensical) 497; sleeveless, idle; pointless, useless etc. 645; inexpedient etc. 647; frivolous etc. (trivial) 643.    ... show more

Roget 24: disagreeing etc. v.; discordant, discrepant; at variance, at war; hostile, antagonistic, repugnant, incompatible, irreconcilable, inconsistent with; unconformable, exceptional etc. 83; intrusive, incongruous; disproportionate, disproportionated^†; inharmonious, unharmonious^†; inconsonant, unconsonant^†; divergent, repugnant to.    inapt, unapt, inappropriate, improper; unsuited, unsuitable; inapplicable, not to the point; unfit, unfitting, unbefitting; unbecoming; illtimed, unseasonable, mal a propos [Fr.], inadmissible; inapposite etc. (irrelevant) 10.    uncongenial; ill-assorted, ill-sorted; mismatched, misjoined^†, misplaced, misclassified; unaccommodating, irreducible, incommensurable, uncommensurable^†; unsympathetic.    out of character, out of keeping, out of proportion, out of joint, out of tune, out of place, out of season, out of its element; at odds with, at variance with.    ... show more

Not conforming to legality, moral law, or social convention:
— Improper banking practices.

synonyms: unconventional, unlawful.

Roget 925: undue; unlawful etc. (illegal) 964; unconstitutional; illicit; unauthorized, unwarranted, disallowed, unallowed^†, unsanctioned, unjustified; unentitled^†, disentitled, unqualified, disqualified; unprivileged, unchartered.    illegitimate, bastard, spurious, supposititious, false; usurped.    tortious [Law].    undeserved, unmerited, unearned; unfulfilled.    forfeited, disfranchised.    improper; unmeet, unfit, unbefitting, unseemly; unbecoming, misbecoming^†; seemless^†; contra bonos mores [Lat.]; not the thing, out of the question, not to be thought of; preposterous, pretentious, would-be.    ... show more

Not appropriate for a purpose or occasion.

synonym: wrong.

Roget 945: vicious; sinful; sinning etc. v.; wicked, iniquitous, immoral, unrighteous, wrong, criminal; naughty, incorrect; unduteous^†, undutiful.    unprincipled, lawless, disorderly, contra bonos mores [Lat.], indecorous, unseemly, improper; dissolute, profligate, scampish; unworthy; worthless; desertless^†; disgraceful, recreant; reprehensible, blameworthy, uncommendable; discreditable, disreputable; Sadistic.    base, sinister, scurvy, foul, gross, vile, black, grave, facinorous^†, felonious, nefarious, shameful, scandalous, infamous, villainous, of a deep dye, heinous; flagrant, flagitious; atrocious, incarnate, accursed.    Mephistophelian, satanic, diabolic, hellish, infernal, stygian, fiendlike^†, hell-born, demoniacal, devilish, fiendish.    miscreated^†, misbegotten; demoralized, corrupt, depraved.    evil-minded, evil-disposed; ill-conditioned; malevolent etc. 907; heartless, graceless, shameless, virtueless; abandoned, lost to virtue; unconscionable; sunk in iniquity, lost in iniquity, steeped in iniquity.    incorrigible, irreclaimable, obdurate, reprobate, past praying for; culpable, reprehensible etc. (guilty) 947.    unjustifiable; indefensible, inexcusable; inexpiable, unpardonable, irremissible^†.    weak, frail, lax, infirm, imperfect; indiscrete; demoralizing, degrading.    ... show more

Roget 923: wrong, wrongful; bad, too bad; unjust, unfair; inequitable, unequitable^†; unequal, partial, one-sided; injurious, tortious [Law].    objectionable; unreasonable, unallowable, unwarrantable, unjustifiable; improper, unfit; unjustified etc. 925; illegal etc. 964; iniquitous; immoral etc. 945.    in the wrong, in the wrong box.    ... show more

Polish: niestosowny