careless vs carefulness

careless is not a noun while carefulness is a noun.

Word	Noun	Adjective	Verb	Adverb
careless	No	Yes	No	No
carefulness	Yes	No	No	No

careless (noun)	carefulness (noun)
	the quality of being careful and painstaking
	the trait of being cautious; being attentive to possible danger

careless (adjective)	carefulness (adjective)
marked by lack of attention or consideration or forethought or thoroughness; not careful
effortless and unstudied
(usually followed by `of') without due thought or consideration