Lacking the thinking capacity characteristic of a conscious being.

Roget 823: insensible, unconscious; impassive, impassible; blind to, deaf to, dead to; unsusceptible, insusceptible; unimpressionable^†, unimpressible^†; passionless, spiritless, heartless, soulless; unfeeling, unmoral.    apathetic; leuco-^†, phlegmatic; dull, frigid; cold blooded, cold hearted; cold as charity; flat, maudlin, obtuse, inert, supine, sluggish, torpid, torpedinous^†, torporific^†; sleepy etc. (inactive) 683; languid, half-hearted, tame; numbed; comatose; anaesthetic etc. 376; stupefied, chloroformed, drugged, stoned; palsy-stricken.    indifferent, lukewarm; careless, mindless, regardless; inattentive etc. 458; neglectful etc. 460; disregarding.    unconcerned, nonchalant, pococurante^†, insouciant, sans souci [Fr.]; unambitious etc. 866.    unaffected, unruffled, unimpressed, uninspired, unexcited, unmoved, unstirred, untouched, unshocked^†, unstruck^†; unblushing etc. (shameless) 885; unanimated; vegetative.    callous, thick-skinned, hard-nosed, pachydermatous, impervious; hardened; inured, casehardened; steeled against, proof against; imperturbable etc. (inexcitable) 826^†; unfelt.    ... show more

Requiring little mental effort.

Not mindful or attentive.

synonyms: forgetful, unmindful.

Roget 458: inattentive; unobservant, unmindful, heedless, unthinking, unheeding, undiscerning^†; inadvertent; mindless, regardless, respectless^†, listless etc. (indifferent) 866; blind, deaf; bird-witted; hand over head; cursory, percursory^†; giddy-brained, scatter-brained, hare-brained; unreflective, unreflecting^†, ecervele [Fr.]; offhand; dizzy, muzzy^†, brainsick^†; giddy, giddy as a goose; wild, harum-scarum, rantipole^†, highflying; heedless, careless etc. (neglectful) 460.    inconsiderate, thoughtless.    absent, abstracted, distrait; absentminded, lost; lost in thought, wrapped in thought; rapt, in the clouds, bemused; dreaming on other things, musing on other things; preoccupied, engrossed etc. (attentive) 457; daydreaming, in a reverie etc. n.; off one's guard etc. (inexpectant) 508^†; napping; dreamy; caught napping.    disconcerted, distracted, put out etc. v.. ... show more

Roget 506: forgotten etc. v.; unremembered, past recollection, bygone, out of mind; buried in oblivion, sunk in oblivion; clean forgotten; gone out of one's head, gone out of one's recollection.    forgetful, oblivious, mindless, Lethean; insensible to the past etc. 823; heedless.    ... show more

Devoid of intelligence or thought.

synonym: vacuous.

Roget 452: vacant, unintellectual, unideal^†, unoccupied, unthinking, inconsiderate, thoughtless, mindless, no-brain, vacuous; absent etc. (inattentive) 458; diverted; irrational etc. 499; narrow-minded etc. 481.    unthought of, undreamt 'of, unconsidered; off one's mind; incogitable^†, not to be thought of.    ... show more

Not marked by the use of reason:
— Mindless violence.

synonyms: reasonless, senseless.

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

Polish: bezsensowy, bezsensowny