Definitions of ambassadorial
a person, especially a well-known person such as a celebrity, who works to increase and improve a company or entity's public profile or who represents or lobbies on behalf of a company or entity
Coe has personally been under fire too over his £100,000-a-year Nike ambassadorial role.
referring to an ambassador (=an important official who lives in a foreign country and represents his or her own country there)
Any nation has the right to reject an ambassadorial candidate proposed by another nation.