An Etymological Dictionary of the German Language/Zapfe
Zapfe, m., ‘peg, plug, tap, bung,’ from MidHG. zapfe, m., ‘tap, espec. in a beer or wine cask’ (also zapfen, ‘to pour out from a tap’), OHG. zapfo, ‘peg, plug.’ Corresponding to North Fris. tâp. Du. tap, AS. tœppa, E. tap, and the equiv. OIc. tappe. From the Teut. cognates are borrowed the equiv. Fr. tape and Ital. zaffo (Spund, on the other hand, was borrowed from Romance). Teut. tappon- cannot be traced back to the other primit. allied languages; only Zipfel seems to be related to these cognates.