C2 noun /ˌpliːnɪpəˈtɛnʃəri/
plenipotentiary
plénipotentiaire
Meaning
a person invested with full power to act on behalf of another, especially in diplomacy
Example
The ambassador was a plenipotentiary sent to negotiate the treaty.
L'ambassadeur était un plénipotentiaire envoyé pour négocier le traité.