sicken vs gag

sicken is not a noun while gag is a noun.

Word	Noun	Adjective	Verb	Adverb
sicken	No	No	Yes	No
gag	Yes	No	Yes	No

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

Other hyponyms of sicken include choke.

sicken (noun)	gag (noun)
	restraint put into a person's mouth to prevent speaking or shouting
	a humorous anecdote or remark intended to provoke laughter

sicken (verb)	gag (verb)
get sick	struggle for breath; have insufficient oxygen intake
make sick or ill	make an unsuccessful effort to vomit; strain to vomit
cause aversion in; offend the moral sense of	cause to retch or choke
upset and make nauseated	make jokes or quips
	be too tight; rub or press
	tie a gag around someone's mouth in order to silence them
	prevent from speaking out