annul vs renege

annul is not a noun while renege is a noun.

Word	Noun	Adjective	Verb	Adverb
annul	No	No	Yes	No
renege	Yes	No	Yes	No

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

Other hyponyms of annul include go back on, renege on, renegue on.

annul (noun)	renege (noun)
	the mistake of not following suit when able to do so

annul (verb)	renege (verb)
cancel officially	fail to fulfill a promise or obligation
declare invalid