fons

Fons, fontis, m., third declension, stem font-. A natural spring where water comes out of the ground, not a built ornamental fountain, and from there the source of anything at all: fons mali, "the root of the trouble", and the tag fons et origo.

Roman springs had their own deities and their own festival, the Fontinalia, so a fons could be a shrine as much as a water supply. Christian Latin narrowed the word again: fons standing alone in this corpus very often means the baptismal font, which is the sense English kept in a church context while keeping fountain for the ornamental one. French fontaine and Italian fonte come from the same word.