Not serious in content or attitude or behavior.

Roget 477: intuitive, instinctive, impulsive; independent of reason, anterior to reason; gratuitous, hazarded; unconnected.    unreasonable, illogical, false, unsound, invalid; unwarranted, not following; inconsequent, inconsequential; inconsistent; absonous^†, absonant^†; unscientific; untenable, inconclusive, incorrect; fallacious, fallible; groundless, unproved; non sequitur [Lat.], it does not follow.    deceptive, sophistical, jesuitical; illusive, illusory; specious, hollow, plausible, ad captandum [Lat.], evasive; irrelevant etc. 10.    weak, feeble, poor, flimsy, loose, vague.    irrational; nonsensical etc. (absurd) 497.    foolish etc. (imbecile) 499; frivolous, pettifogging, quibbling; finespun^†, overrefined^†.    at the end of one's tether, au bout de son latin.    ... 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 608: capricious; erratic, eccentric, fitful, hysterical; full of whims etc. n.; maggoty; inconsistent, fanciful, fantastic, whimsical, crotchety, kinky [U.S.], particular, humorsome^†, freakish, skittish, wanton, wayward; contrary; captious; arbitrary; unconformable etc. 83; penny wise and pound foolish; fickle etc. (irresolute) 605; frivolous, sleeveless, giddy, volatile.    ... show more

Roget 643: unimportant; of little account, of small account, of no account, of little importance, of no importance etc. 642; immaterial; unessential, nonessential; indifferent.    subordinate etc. (inferior) 34; mediocre etc. (average) 29; passable, fair, respectable, tolerable, commonplace; uneventful, mere, common; ordinary etc. (habitual) 613; inconsiderable, so-so, insignificant, inappreciable.    trifling, trivial; slight, slender, light, flimsy, frothy, idle; puerile etc. (foolish) 499; airy, shallow; weak etc. 160; powerless etc. 158; frivolous, petty, niggling; piddling, peddling; fribble^†, inane, ridiculous, farcical; finical, finikin^†; fiddle-faddle, fingle-fangle^†, namby-pamby, wishy-washy, milk and water.    poor, paltry, pitiful; contemptible etc. (contempt) 930; sorry, mean, meager, shabby, miserable, wretched, vile, scrubby, scrannel^†, weedy, niggardly, scurvy, putid^†, beggarly, worthless, twopennyhalfpenny, cheap, trashy, catchpenny, gimcrack, trumpery; one-horse [U.S.].    not worth the pains, not worth while, not worth mentioning, not worth speaking of, not worth a thought, not worth a curse, not worth a straw etc. n.; beneath notice, unworthy of notice, beneath regard, unworthy of regard, beneath consideration, unworthy of consideration; de lana caprina [It]; vain etc. (useless) 645.    ... show more

Dutch: frivool