interject vs interjection

interject is not a noun while interjection is a noun.

Word	Noun	Adjective	Verb	Adverb
interject	No	No	Yes	No
interjection	Yes	No	No	No

interject (noun)	interjection (noun)
	the action of interjecting or interposing an action or remark that interrupts
	an abrupt emphatic exclamation expressing emotion

interject (verb)	interjection (verb)
to insert between other elements