English 'fountain' from Old French 'fontaine,' from Latin 'fōns' (spring, source), from PIE *dʰen- (to flow).
A structure from which water springs or flows for drinking or ornamental purposes; a natural spring of water.
From Old French 'fontaine' (fountain, natural spring, source of water), from Late Latin 'fontāna' (a spring, a fountain), the feminine of 'fontānus' (of a spring), derived from Latin 'fōns' (genitive 'fontis', a spring, a source of flowing water). The PIE root is *dʰen- (to run, to flow), related to *dʰew- (to flow, to run), which also underlies Sanskrit 'dhā-' (river), Avestan 'dānu-' (river), Old Irish 'sruth' (stream), and the great river names Dnieper, Dniester, Don, and Danube — all deriving from the PIE root for flowing water. The Latin 'fōns' gave 'font' (a baptismal basin, where water was poured
The typographic 'font' and the baptismal 'font' are actually different words that happen to look alike. The baptismal font comes from Latin 'fōns' (spring) — it is a basin containing the 'spring' of baptismal water. The typographic 'font' (or 'fount') comes from French 'fonte' (a casting), from 'fondre' (to melt, to cast metal), because letters were cast in molten metal. They converged to the same spelling by coincidence.