Foster-Brother
From BiblePortal Wikipedia
Foster-Brother [1]
1: σύντροφος (Strong'S #4939 Adjective suntrophos soon'-trof-os )
primarily denotes "one nourished or brought up with another" (sun, "with," trepho, "to rear"); it is rendered "foster-brother" in Acts 13:1 , Rv. It has, however, been found in Hellenistic usage as a court term, signifying an intimate friend of a king (Deissmann), and this would seem to be the meaning regarding Manaen and Herod the Tetrarch.