marked by lack of attention or consideration or forethought or thoroughness; not careful
"careless about her clothes"
"forgotten by some careless person"
"a careless housekeeper"
"careless proofreading"
"it was a careless mistake"
"hurt by a careless remark"
(usually followed by `of') without due thought or consideration
"careless of the consequences"
"crushing the blooms with regardless tread"
Not concerned or worried (about).
"He was so careless about his safety that he forgot to wear a helmet while riding his bike."