A person formally commissioned (alone, or as one of a party) to convey a message from or to a monarch or other authority; especially a minister of high rank sent on a diplomatic or political mission by one monarch or state to another.

An appointed or official messenger; a person who speaks or acts on another's behalf; a person's (or God's) representative; = "ambassador". Also (and in earliest use): a representative or advocate of a specified quality or virtue.

A diplomat of the highest rank permanently representing a monarch or state in a foreign court or state; = "ambassador".