[ ˌplɛnɪpə'tɛnʃ(ə)ri ]
■ noun ( plural plenipotentiaries ) a person, especially a diplomat, who is invested with the full power of independent action on behalf of their government.
■ adjective having full power to take independent action.
↘(of power) absolute.
Origin
C17: from med. L. plenipotentiarius , from plenus 'full' + potentia 'power'.