fountainyoudaoicibaDictYouDict[fountain 词源字典]
fountain: [15] Latin fons meant ‘spring of water’ (it was related to Sanskrit dhan- ‘run, flow’). The feminine form of its adjectival derivative, fontāna ‘of a spring’, came to be used in late Latin as a noun, also meaning ‘spring’, and this passed via Old French fontaine into English, still carrying its original sense ‘spring’ with it. This survives in the reduced form fount [16], which is usually used metaphorically for a ‘source’, but fountain itself has from the 16th century been mainly applied to an ‘artificial jet of water’.

Other descendants of Latin fontāna, incidentally, include Italian fontana, Romanian fîntîna, and Welsh ffynon. Fontanelle ‘space between infant’s skull bones’ [16] comes ultimately from Old French fontenelle, a diminutive form of fontaine. The underlying notion appears to be of an anatomical ‘hollow’, as if from which a spring of water would come.

=> fontanelle, fount[fountain etymology, fountain origin, 英语词源]
fountain (n.)youdaoicibaDictYouDict
early 15c., "spring of water that collects in a pool," from Old French fontaine "natural spring" (12c.), from Medieval Latin fontana "fountain, a spring" (source of Spanish and Italian fontana), from post-classical noun use of fem. of Latin fontanus "of a spring," from fons (genitive fontis) "spring (of water)," from PIE root *dhen- (1) "to run, flow" (cognates: Sanskrit dhanayati, Old Persian danuvatiy "flows, runs").

The extended sense of "artificial jet of water" (and the structures that make them) is first recorded c. 1500. Hence also fountain-pen (by 1823), so called for the reservoir that supplies a continuous flow of ink. "A French fountain-pen is described in 1658 and Miss Burney used one in 1789" [Weekley]. Fountain of youth, and the story of Ponce de Leon's quest for it, seem to have been introduced in American English by Hawthorne's "Dr. Heidegger's Experiment" (January 1837).
"Did you never hear of the 'Fountain of Youth'?" asked Dr. Heidegger, "which Ponce de Leon, the Spanish adventurer, went in search of two or three centuries ago?"