from ἀρχή and ἱερεύς; the high-priest (literally, of the Jews, typically, Christ); by extension a chief priest:--chief (high) priest, chief of the priests.
neuter of a presumed derivative of a compound of σύν and the base of ἑδραῖος; a joint session, i.e. (specially), the Jewish Sanhedrin; by analogy, a subordinate tribunal:--council.