Marked by lack of attention or consideration or forethought or thoroughness; not careful.

Roget 460: neglecting etc. v.; unmindful, negligent, neglectful; heedless, careless, thoughtless; perfunctory, remiss; feebleness etc. 575.    inconsiderate; uncircumspect^†, incircumspect^†; off one's guard; unwary, unwatchful^†, unguarded; offhand.    supine etc. (inactive) 683; inattentive etc. 458; insouciant etc. (indifferent) 823; imprudent, reckless etc. 863; slovenly etc. (disorderly) 59, (dirty) 653; inexact etc. (erroneous) 495; improvident etc. 674.    neglected etc. v.; unheeded, uncared-for, unperceived, unseen, unobserved, unnoticed, unnoted^†, unmarked, unattended to, unthought of, unregarded^†, unremarked, unmissed^†; shunted, shelved.    unexamined, unstudied, unsearched^†, unscanned^†, unweighed^†, unsifted, unexplored.    abandoned; buried in a napkin, hid under a bushel.    ... show more

Roget 575: feeble, bald, tame, meager, jejune, vapid, bland, trashy, lukewarm, cold, frigid, poor, dull, dry, languid; colorless, enervated; proposing, prosy, prosaic; unvaried, monotonous, weak, washy, wishy-washy; sketchy, slight.    careless, slovenly, loose, lax (negligent) 460; slipshod, slipslop^†; inexact; puerile, childish; flatulent; rambling etc. (diffuse) 573.    ... show more

Roget 863: rash, incautious, indiscreet; imprudent, improvident, temerarious; uncalculating^†; heedless; careless etc. (neglectful) 460; without ballast, heels over head, head over heels; giddy etc. (inattentive) 458; wanton, reckless, wild, madcap; desperate, devil-may-care.    hot-blooded, hotheaded, hotbrained^†; headlong, headstrong; breakneck; foolhardy; harebrained; precipitate, impulsive.    overconfident, overweening; venturesome, venturous; adventurous, Quixotic, fire eating, cavalier; janty^†, jaunty, free and easy.    off one's guard etc. (inexpectant) 508^†.    ... show more

Roget 866: indifferent, cold, frigid, lukewarm; cool, cool as a cucumber; unconcerned, insouciant, phlegmatic, pococurante^†, easygoing, devil-may-care, careless, listless, lackadaisical; half-hearted; unambitious, unaspiring, undesirous^†, unsolicitous^†, unattracted.    [indifferent toward people] aloof, unapproachable, remote; uncaring.    unattractive, unalluring, undesired, undesirable, uncared for, unwished^†, unvalued, all one to.    insipid etc. 391; vain.    ... show more

Polish: beztroski, niefrasobliwy, niepoważny, lekki, lekkoduszny, lekkomyślny

Effortless and unstudied.

usually followed by `of' Without due thought or consideration:
— Careless of the consequences.

synonym: regardless.

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 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