The word "pontifex" and its derivative "pontiff" later became terms used for Christian bishops, including the Bishop of Rome, and the title of "Pontifex Maximus" was applied within the Catholic Church to the Pope as its chief bishop and appears on buildings, monuments and coins of popes of Renaissance and modern times. The official list of titles of the Pope given in the Annuario Pontificio includes "Supreme Pontiff" (in Latin, Summus Pontifex) as the fourth title, the first being "Bishop of Rome".
The etymology of "pontifex" is uncertain, and has been since Roman times. The word appears to consist of the Latin word for "bridge" and the suffix for "maker". However, there is a possibility that this definition is a folk etymology for an Etruscan term, since Roman religion was heavily influenced by Etruscan religion, and very little is known about the Etruscan language, which is not Indo-European.
According to the common interpretation, the term pontifex means "bridge-builder" (pons + facere); "maximus" means "greatest". This was perhaps originally meant in a literal sense: the position of bridge-builder was indeed an important one in Rome, where the major bridges were over the Tiber, the sacred river (and a deity): only prestigious authorities with sacral functions could be allowed to "disturb" it with mechanical additions. However, it was always understood in its symbolic sense as well: the pontifices were the ones who smoothed the "bridge" between gods and men.
The interpretation of the word pontifex as "bridge-builder" was that of Dionysius of Halicarnassus and Marcus Terentius Varro. Plutarch pointed out that the term existed before there were any bridges in Rome and derived the word from Old Latin pontis (sic) meaning a powerful or absolute master, while others derived it from potis facere in the sense of "able to sacrifice". The last derivation is mentioned also by Varro, who rejected it, but it was the view of Pontifex Maximus Quintus Scaevola. Others have held that the word was originally pompifex (leader of public processions). The word pons originally meant "way" and pontifex would thus mean "maker of roads and bridges".