defame vs libel

defame is not a noun while libel is a noun.

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

As verbs, libel is a hyponym of defame; that is, libel is a word with a more specific, narrower meaning than defame:

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

Other hyponyms of defame include assassinate, badmouth, drag through the mud, malign, traduce.

defame (noun)	libel (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

defame (verb)	libel (verb)
charge falsely or with malicious intent; attack the good name and reputation of someone	print slanderous statements against