Webster's Revised Unabridged Dictionary · 1913

Diplomatic

Diplomatic , adjective

[Compare diplomatique.]

1.
Pertaining to diplomacy; relating to the foreign ministers at a court, who are called the diplomatic body.
2.
Characterized by tact and shrewdness; dexterous; artful; as, diplomatic management.
3.
Pertaining to diplomatics; paleographic. — Astle

Also: Diplomatical

Diplomatic , noun

A minister, official agent, or envoy to a foreign court; a diplomatist.