intermediary vs intermediator

intermediary and intermediator both are nouns.

Word	Noun	Adjective	Verb	Adverb
intermediary	Yes	No	No	No
intermediator	Yes	No	No	No

As nouns, intermediary and intermediator are synonyms defined as:

intermediary and intermediator: a negotiator who acts as a link between parties

Other synonyms of intermediary include go-between, intercessor, mediator.

intermediary (noun)	intermediator (noun)
a negotiator who acts as a link between parties	a negotiator who acts as a link between parties