Adversary
ad’-ver-sa-ri, ad’-ver-sa-ri: This word (in the singular or plural) is used in the Old Testament to render different Hebrew words. In thirty-two cases the word corresponds to the noun tsar, or the verb tsarar. This noun is the ordinary word for "foe" or "adversary." In twelve passages the Hebrew word, of which "adversary" is the translation, is saTan = noun or saTan = verb. This stem means "to oppose," or "thwart" anyone in his purpose or claims.
In the New Testament "adversary" represents:
(1) antikeimenoi, the participle of a verb which means "to be set over against," "to be opposed" (Lu 13:17; Php 2:8).
(2) antidikos, "opponent in a lawsuit," "prosecutor" (Mt 5:25; Lu 12:58; 18:3; 1Pe 5:8).
According to the last passage the devil is the "accuser" or "prosecutor" of believers, but according to another writer they have an "advocate" or "counselor for the defense" with the Father (1Jo 2:1). In one passage (Heb 10:27) "adversary" represents a Greek word, hupenantios, which means "set over against," "contrary to"--a word used in classical Greek and in the Septuagint.