A minister of the highest rank sent to a foreign court to represent there his sovereign or country. (Sometimes called ambassador-in-residence)
1982, Orville T. Murphy, Charles Gravier, Comte de Vergennes: French Diplomacy in the Age of Revolution, 1719-1787:
Vergenne'fury reached its height when the priest tried to involve the English ambassador.
An official messenger and representative.
1856, Mrs. William Busk, Mediæval Popes, Emperors, Kings, and Crusaders: Or, Germany, Italy and Palestine, from A.D. 1125 to A.D. 1268, volume IV, London: Hookham and Sons, OCLC2480341, page 294:
The new accusation brought by Urban against Manfred of murdering his sister-in-law's embassador – it may be observed that, tacitly, he acquits him of parricide, fratricide, and nepoticide – requires a little explanation.
A corporate representative, often the public face of the company.
(archaic, slang) A trick to duck some ignorant fellow or landsman, frequently played on board ships in the warm latitudes. It is thus managed: A large tub is filled with water, and two stools placed on each side of it. Over the whole is thrown a tarpaulin, or old sail: this is kept tight by two persons, who are to represent the king and queen of a foreign country, and are seated on the stools. The person intended to be ducked plays the Ambassador, and after repeating a ridiculous speech dictated to him, is led in great form up to the throne, and seated between the king and queen, who rising suddenly as soon as he is seated, he falls backwards into the tub of water.