1) chief priest, high priest

 He above all others was honoured with the title of priest, the chief
 of priests. It was lawful for him to perform the common duties of
 the priesthood; but his chief duty was, once a year on the day of
 atonement, to enter into the Holy of Holies (from which the other
 priests were excluded) and offer sacrifices for his own sins and the
 sins of the people, and to preside over the Sanhedrin, or Supreme
 Council, when convened for judicial deliberations. According to
 Mosaic law, no one could aspire to the high priesthood unless he
 were of the tribe of Aaron and descended from a high priestly
 family; and he on whom the office was conferred held it till death.
 But from the time of Antiochus Epiphanes, when the kings of
 Seleucideae and afterwards the Herodian princes and the Romans
 arrogated to themselves the power of appointing the high priests,
 the office neither remained vested in the pontifical family nor was
 conferred on any for life; but it became venal, and could be
 transferred from one to another according to the will of civic or
 military rulers. Hence it came to pass, that during the one hundred
 and seven years intervening between Herod the Great and the
 destruction of the holy city, twenty eight persons held the
 pontifical dignity.  2) the high priests, these comprise in addition
 to one holding the high priestly office, both those who had
 previously discharged it and although disposed, continued to have
 great power in the State, as well as the members of the families
 from which high priest were created, provided that they had much
 influence in public affairs.  3) Used of Christ because by
 undergoing a bloody death he offered himself as an expiatory
 sacrifice to God, and has entered into the heavenly sanctuary where
 he continually intercedes on our behalf.