What is another word for "plenipotentiary"?

Roget's Thesaurus (1911) lists these synonyms for "plenipotentiary": ablegate, accredit, acting, advocate, agent, alter, ambassador, answer, appear, arbitrator, archon, attache, attorney, auctioneer, bagman, bailiff, behalf, brief, broker, business, champion, chancellor, charge, clerk, commercial, commissary, commission, commissionaire, commissioner, committee, consignee, consul, corps, correspondent, curator, delegate, deputy, diplomat, diplomate, diplomatist.