Definition of ambassage in English:

ambassage

Pronunciation /ˈambəsɪdʒ/

noun

rare
  • The business or function of an ambassador.

    Formerly also in "†in (also of) ambassage": in the role of ambassador; on a diplomatic mission (obsolete).

Origin

Mid 16th century; earliest use found in Shearmen & Taylors' Pageant. Apparently an alteration (with suffix substitution) of ambassade.