embassy

[em-buh-see] /ˈɛm bə si/
noun, plural embassies.
1.
a body of persons entrusted with a mission to a sovereign or government, especially an ambassador and his or her staff.
2.
the official headquarters of an ambassador.
3.
the function or office of an ambassador.
4.
a mission headed by an ambassador.
Origin
1570-80; variant of ambassy < Middle French ambassee, Old French ambasce, ambaxee ≪ Old Provençal ambaissada, derivative of embayssar to send a delegate < Medieval Latin ambasciāre, derivative of ambascia service, office, derivative, by a Gmc intermediary (compare Gothic andbahti, Old High German ambahti) of Gallo-Latin ambactus retainer, servant (< Gaulish, equivalent to amb- around, ambi- + -act- verbal adjective of *ag- drive, lead; cf. act, Welsh amaeth husbandman); cf. ambassador
British Dictionary definitions for embassy

embassy

/ˈɛmbəsɪ/
noun (pl) -sies
1.
the residence or place of official business of an ambassador
2.
an ambassador and his entourage collectively
3.
the position, business, or mission of an ambassador
4.
any important or official mission, duty, etc, esp one undertaken by an agent
Word Origin
C16: from Old French ambassee, from Old Italian ambasciata, from Old Provençal ambaisada, ultimately of Germanic origin; see ambassador
Word Origin and History for embassy
n.

1570s, "position of an ambassador," from Middle French embassee "mission, charge, office of ambassador," Old French ambassee, from Italian ambasciata, from Old Provençal ambaisada "office of ambassador," from Gaulish *ambactos "dependant, vassal," literally "one going around," from PIE *amb(i)-ag-to, from *ambi- (see ambi-) + *ambi- "around" (see ambi-) + *ag- "to drive, move" (see act (n.)).

Meaning "official residence and retinue of an ambassador" is from 1764. In earlier use were embassade (late 15c.), ambassade (early 15c.).