Adjective: Plenipotentiary (plen-uh-puh-TEN-shuh-ree)
Definition:
1. Invested with full power.
2. Of or relating to a person invested with full power to transact any business.
Sample sentence: The CEO of the large company, about to leave for a month-long vacation, assured his board of directors that his assistant had his full confidence and was vested with plenipotentiary powers.