embassy (n.) Look up embassy at Dictionary.com
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.).