Where does “fontānus” come from?

fontānus (Latin) comes from Latin fons, from Latin fontis — genitive singular of fōns.

Ancestry of “fontānus”, step by step

Step	Language	Word	Meaning
1	Latin	fons	a spring, a fountain; fresh water, spring water;...
2	Latin	fontis	genitive singular of fōns

fontānus — Etymology, Origin & Word History | Etymology Explorer