negociate vs mediate

negociate is not an adjective while mediate is an adjective.

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

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

Other hyponyms of negociate include arbitrate, intercede, intermediate, liaise, renegociate, renegotiate, bargain, dicker, broker.

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

negociate (verb)	mediate (verb)
discuss the terms of an arrangement	act between parties with a view to reconciling differences
confer with another in order to come to terms or reach an agreement	occupy an intermediate or middle position or form a connecting link or stage between two others
succeed in passing through, around, or over
transfer by endorsement to another in return for value received
sell or discount
be successful; achieve a goal