immediacy vs mediate

immediacy is a noun but mediate is not a noun.

Word	Noun	Adjective	Verb	Adverb
immediacy	Yes	No	No	No
mediate	No	Yes	Yes	No

immediacy (noun)	mediate (noun)
the quickness of action or occurrence
lack of an intervening or mediating agency
immediate intuitive awareness

immediacy (adjective)	mediate (adjective)
	acting through or dependent on an intervening agency
	being neither at the beginning nor at the end in a series

immediacy (verb)	mediate (verb)
	act between parties with a view to reconciling differences
	occupy an intermediate or middle position or form a connecting link or stage between two others