mid-14c., aduersere, from Anglo-French adverser (13c.), Old French adversaire "adversary, opponent, enemy," or directly from Latin adversarius "opponent, adversary, rival," noun use of adjective meaning "opposite, hostile, contrary," literally "turned toward one," from adversus "turned against" (see adverse). The Latin word is glossed in Old English by wiðerbroca.
(Heb. satan), an opponent or foe (1 Kings 5:4; 11:14, 23, 25; Luke 13:17); one that speaks against another, a complainant (Matt. 5:25; Luke 12:58); an enemy (Luke 18:3), and specially the devil (1 Pet. 5:8).