plenipotentiary

[plen-uh-puh-ten-shee-er-ee, -shuh-ree] /ˌplɛn ə pəˈtɛn ʃiˌɛr i, -ʃə ri/
noun, plural plenipotentiaries.
1.
a person, especially a diplomatic agent, invested with full power or authority to transact business on behalf of another.
adjective
2.
invested with full power or authority, as a diplomatic agent.
3.
conferring or bestowing full power, as a commission.
4.
absolute or full, as power.
Origin
1635-45; < Medieval Latin plēnipotentiārius. See plenipotent, -i-, -ary
British Dictionary definitions for plenipotentiary

plenipotentiary

/ˌplɛnɪpəˈtɛnʃərɪ/
adjective
1.
(esp of a diplomatic envoy) invested with or possessing full power or authority
2.
conferring full power or authority
3.
(of power or authority) full; absolute
noun (pl) -aries
4.
a person invested with full authority to transact business, esp a diplomat authorized to represent a country See also envoy1 (sense 1)
Word Origin
C17: from Medieval Latin plēnipotentiārius, from Latin plēnus full + potentiapower
Word Origin and History for plenipotentiary
adj.

1640s, from French plénipotentiaire and directly from Medieval Latin plenipotentiarius "having full power," from Late Latin plenipotens, from Latin plenus "full" (see plenary) + potentem "powerful" (see potent). As a noun from 1650s.