1610, "high priest," from Fr.
pontif (1516), from L.
pontifex, title of a Roman high priest (see
pontifex). Used for "bishop" in Church Latin, but not recorded in that sense in Eng. until 1677, specifically "the bishop of Rome," the pope.
Pontifical, however, is used with this sense from c.1440.
Pontificate (v.) "issue dogmatic decrees" is first attested 1825.