Pontifex, as a term to describe the chief priest of the Roman people, has very obscure origins. One theory holds that the word comes from the Latin “pons” and “facere” meaning something like “bridgebuilder”. This reading may refer to a sort of spiritual bridge between this world and the divine that the pontifex is responsible for maintaining. Another theory holds that the bridge in question refers to the first bridge ever built over the Tiber River by the semi-mythical fourth king of Rome, Ancus Marcius. This theory seems to make sense as Ancus Marcius also ordered the chief priest of Rome to copy the instructions for how to sacrifice to the gods properly and display these instructions publicly on wooden tablets. 

But there are others who don’t read the term as having anything to do with bridges at all. Other Latin writers believed the word to be from the Oscan-Umbrian word “puntis” meaning to sacrifice. Yet still others favor an Etruscan origin for the term since they did have a strong influence over early Roman religious practice. The Etruscan language, however, is largely lost to us now. Whatever that meaning could have had is lost to history.