monstrous vs evil

monstrous is not a noun while evil is a noun.

Word	Noun	Adjective	Verb	Adverb
monstrous	No	Yes	No	No
evil	Yes	Yes	No	No

monstrous (noun)	evil (noun)
	morally objectionable behavior
	the quality of being morally wrong in principle or practice

monstrous (adjective)	evil (adjective)
shockingly brutal or cruel	morally bad or wrong
abnormally large	having or exerting a malignant influence
distorted and unnatural in shape or size; abnormal and hideous	having the nature of vice