diplomat vs diplomatist

diplomat and diplomatist both are nouns.

Word	Noun	Adjective	Verb	Adverb
diplomat	Yes	No	No	No
diplomatist	Yes	No	No	No

As nouns, diplomat and diplomatist are synonyms defined as:

diplomat and diplomatist: an official engaged in international negotiations

diplomat (noun)	diplomatist (noun)
an official engaged in international negotiations	an official engaged in international negotiations
a person who deals tactfully with others