Synonyms and related words :
airy, brash, careless, casual, cursory, degage, disregardant, disregardful, easygoing, flippant, forgetful, free and easy, heedless, impolitic, inconsiderate, indifferent, insouciant, lazy, maladroit, oblivious, offhand, perfunctory, reckless, regardless, respectless, tactless, thoughtless, unheedful, unheeding, unmindful, unprepared, unready, unsolicitous, untactful, unthinking