Source : Webster's Revised Unabridged Dictionary (1913)

Diplomat \Dip"lo*mat\, Diplomate \Dip"lo*mate\, n. [F.
   diplomate.]
   A diplomatist.

Diplomate \Dip"lo*mate\, v. t.
   To invest with a title o? privilege by diploma. [R.] --Wood.

Source : WordNet®

diplomate
     n : medical specialist whose competence has been certified by a
         diploma granted by an appropriate professional group