Careless
Incautious
Synonyms: Inattentive, negligent, forgetful, heedless, impetuous, sloppy, slap-happy, slapdash, scrappy, unconsidered, lax, wild, hasty, perfunctory, thrown together, hit-or-miss, imprecise, incorrect, erroneous, scatterbrained, unthinking, indiscreet, ill-advised, ill-thought-out, misguided, rash, spur-of-the-moment, negligent in, heedless of, unconcerned about, oblivious to, remiss in, slipshod about, sloppy in, incautious, remiss, absent-minded, irresponsible, reckless, couldn't care less, shoddy, slipshod, slovenly, amateurish, slack, disorganized, hurried, cursory, sketchy, inaccurate, inexact, wrong, error-ridden, thoughtless, insensitive, unguarded, ill-considered, unwise, inadvertent, foolhardy, hare-brained, mindless of, improvident about, indifferent to, reckless about, slapdash about, frivolous about, and messy in.
Artless
Synonyms: Unstudied, casual, unconcerned, insouciant, leisurely, couldn't-care-less, artless, effortless, nonchalant, languid, and informal.
Example Sentences
His careless mistakes cost him dearly.
She was careless with her belongings.
Careless driving can lead to accidents.
They made a careless decision yesterday.