legate(n = noun.person) official emissary - a member of a legation;
is a kind of emissary, envoy
is a member of foreign mission, legation
Derived form noun legateship₁

1.  An ambassador or envoy. [1913 Webster]

2.  An ecclesiastic representing the pope and invested with the authority of the Holy See. [1913 Webster]
" Legates are of three kinds: (a) Legates a latere, now always cardinals. They are called ordinary or extraordinary legates, the former governing provinces, and the latter class being sent to foreign countries on extraordinary occasions. (b) Legati missi, who correspond to the ambassadors of temporal governments. (c) Legati nati, or legates by virtue of their office, as the archbishops of Salzburg and Prague." [1913 Webster]

3.  An official assistant given to a general or to the governor of a province. [1913 Webster]

legate, n.
1 a member of the clergy representing the Pope.
2 Rom.Hist. a a deputy of a general. b a governor or deputy governor of a province.
3 archaic an ambassador or delegate.

Idiom:
legate a latere a papal legate of the highest class, with full powers.

Derivative:
legateship n. legatine adj.

Etymology:
OE f. OF legat f. L legatus past part. of legare depute, delegate

N  consignee, trustee, nominee, committee, agent, delegate, commissary, commissioner, emissary, envoy, commissionaire, messenger, diplomatist, diplomat, diplomate, corps diplomatique, embassy, ambassador, embassador, representative, resident, consul, legate, nuncio, internuncio, charge d'affaires, attache, vicegerent, plenipotentiary, functionary, placeman, curator, treasurer, factor, bailiff, clerk, secretary, attorney, advocate, solicitor, proctor, broker, underwriter, commission agent, auctioneer, one's man of business, factotum, caretaker, dalal, dubash, garnishee, gomashta, negotiator, go-between, middleman, under agent, employe, servant, referee, arbitrator, traveler, bagman, commis-voyageur, touter, commercial traveler, drummer, traveling man, newspaper correspondent, own correspondent, special correspondent.

N  messenger, envoy, emissary, legate, nuncio, internuncio, ambassador, marshal, flag bearer, herald, crier, trumpeter, bellman, pursuivant, parlementaire, apparitor, courier, runner, dak, estafette, Mercury, Iris, Ariel, commissionaire, errand boy, chore boy, newsboy, mail, overnight mail, express mail, next-day delivery, post, post office, letter bag, delivery service, United Parcel Service, UPS, Federal Express, Fedex, telegraph, telephone, cable, wire (electronic information transmission), carrier pigeon, (news) 532 reporter, gentleman of the press, representative of the press, penny-a-liner, special correspondent, own correspondent, spy, scout, informer.