libel vs denigrate

libel is a noun but denigrate is not a noun.

Word	Noun	Adjective	Verb	Adverb
libel	Yes	No	Yes	No
denigrate	No	No	Yes	No

As verbs, denigrate is a hypernym of libel; that is, denigrate is a word with a broader meaning than libel:

libel: print slanderous statements against
denigrate: charge falsely or with malicious intent; attack the good name and reputation of someone

Other hypernyms of libel include asperse, besmirch, calumniate, defame, slander, smear, smirch, sully.

libel (noun)	denigrate (noun)
a false and malicious publication printed for the purpose of defaming a living person
the written statement of a plaintiff explaining the cause of action (the defamation) and any relief he seeks

libel (verb)	denigrate (verb)
print slanderous statements against	cause to seem less serious; play down
	charge falsely or with malicious intent; attack the good name and reputation of someone