Noun
A person employed in, or skilled in, diplomacy; a diplomat.
Source: Webster's dictionaryTo make a good salad is to be a brilliant diplomatist -- the problem is entirely the same in both cases. To know exactly how much oil one must put with one's vinegar. Oscar Wilde
PLENIPOTENTIARY, adj. Having full power. A Minister Plenipotentiary is a diplomatist possessing absolute authority on condition that he never exert it. Ambrose Bierce