Source : Webster's Revised Unabridged Dictionary (1913)

Diplomatist \Di*plo"ma*tist\, n. [Cf. F. diplomatiste a student
   of diplomatics.]
   A person employed in, or skilled in, diplomacy; a diplomat.

         In ability, Avaux had no superior among the numerous
         able diplomatics whom his country then possessed.
                                                  --Macaulay.

Source : WordNet®

diplomatist
     n : an official engaged in international negotiations [syn: {diplomat}]