merciless vs mortal

merciless is not a noun while mortal is a noun.

Word	Noun	Adjective	Verb	Adverb
merciless	No	Yes	No	No
mortal	Yes	Yes	No	No

merciless (noun)	mortal (noun)
	a human being; person, singular, assertive existential pronoun; pronoun, person, singular; quantifier: assertive existential

merciless (adjective)	mortal (adjective)
having or showing no mercy	subject to death
	unrelenting and deadly
	involving loss of divine grace or spiritual death
	causing or capable of causing death