not paying enough attention to what one does

a careless typist.

not exact, accurate, or thorough

careless work.

done or said heedlessly or negligently; unconsidered

a careless remark.

not caring or troubling; having no care or concern; unconcerned (usually fol. by of, about, or in )

careless of the rights of others; careless about one's behavior; careless in speech.

possessed or caused without effort or art; unstudied

careless beauty.

Archaic . free from anxiety.

adjective

accurate , attentive , careful , cautious , concerned , mindful , painstaking , prudent , ready , thoughtful , guarded , kind , scrupulous

adjective

absent-minded , abstracted , casual , cursory , disregardful , forgetful , hasty , heedless , improvident , imprudent , inaccurate , inadvertent , incautious , inconsiderate , indifferent , indiscreet , indolent , injudicious , irresponsible , lackadaisical , lax , loose , mindless , napping , negligent , nonchalant , oblivious , offhand , perfunctory , pococurante , reckless , regardless , remiss , slipshod , sloppy , thoughtless , uncircumspect , unconcerned , unguarded , unheeding , unmindful , unobservant , unreflective , unthinking , wastefulnotes:carefree means free of trouble and worry and care while careless means marked by lack of attention or consideration or forethought or thoroughness; not careful , modest , naive , natural , simple , unstudiednotes:carefree means free of trouble and worry and care while careless means marked by lack of attention or consideration or forethought or thoroughness; not careful , feckless , inattentive , messy , slapdash , slovenly , untidy , absentminded , apathetic , clumsy , cool , desultory , devil-may-care , disorderly , easy , haphazard , harum-scarum , impetuous , incurious , languid , listless , neglectful , precipitate , promiscuous , random , rash , slack , spontaneous , superficial , supine , unfit , unsolicitous , unwary , wasteful