mindlessness vs mindless

mindlessness is a noun but mindless is not a noun.

Word	Noun	Adjective	Verb	Adverb
mindlessness	Yes	No	No	No
mindless	No	Yes	No	No

mindlessness (noun)	mindless (noun)
the trait of acting rashly and without prudence
total lack of meaning or ideas

mindlessness (adjective)	mindless (adjective)
	not mindful or attentive
	devoid of intelligence or thought
	lacking the thinking capacity characteristic of a conscious being
	requiring little mental effort
	not marked by the use of reason