late 14c., also embassador, from Middle French ambassadeur, from Old French embassator, via Provençal or Old Spanish from Latin ambactus "a servant, vassal," from Celtic amb(i)actos "a messenger, servant," from PIE *ambhi- "about" (see ambi-) + *ag- "drive, lead" (see act (v.)). Cf. embassy. Forms in am- and em- were used indiscriminately 17c.-18c.
In the Old Testament the Hebrew word _tsir_, meaning "one who goes on an errand," is rendered thus (Josh. 9:4; Prov. 13:17; Isa. 18:2; Jer. 49:14; Obad. 1:1). This is also the rendering of _melits_, meaning "an interpreter," in 2 Chr. 32:31; and of _malak_, a "messenger," in 2 Chr. 35:21; Isa. 30:4; 33:7; Ezek. 17:15. This is the name used by the apostle as designating those who are appointed by God to declare his will (2 Cor. 5:20; Eph. 6:20). The Hebrews on various occasions and for various purposes had recourse to the services of ambassadors, e.g., to contract alliances (Josh. 9:4), to solicit favours (Num. 20:14), to remonstrate when wrong was done (Judg. 11:12), to condole with a young king on the death of his father (2 Sam. 10:2), and to congratulate a king on his accession to the throne (1 Kings 5:1). To do injury to an ambassador was to insult the king who sent him (2 Sam. 10:5).