Webster's Revised Unabridged Dictionary · 1913

Embassy

Embassy , noun

[Old French ambassée, embascée, Late Latin ambasciata, from ambasciare for ambactiare to go on a mission, from Latin ambactus vassal, dependent, of Celtic or German origin; compare Welsh amaeth husbandman, Gothic andbahts servant, German amt office, Old High German ambaht. Compare Ambassador.]

1.
The public function of an ambassador; the charge or business intrusted to an ambassador or to envoys; a public message to; foreign court concerning state affairs; hence, any solemn message.
He sends the angels on embassies with his decrees. — Jer. Taylor
2.
The person or persons sent as ambassadors or envoys; the ambassador and his suite; envoys.
3.
The residence or office of an ambassador.

Sometimes, but rarely, spelled ambassy.