informant vs inform

informant is a noun but inform is not a noun.

Word	Noun	Adjective	Verb	Adverb
informant	Yes	No	No	No
inform	No	No	Yes	No

informant (noun)	inform (noun)
a person who supplies information
someone who sees an event and reports what happened

informant (verb)	inform (verb)
	give character or essence to
	impart knowledge of some fact, state of affairs, or event to
	act as an informer