An Etymological Dictionary of the German Language/Annotated/falzen
falzen, verb, ‘to fold, groove, rabbet,’ from Middle High German velzen, valzen, Old High German falzen, ‘to fold’; Falz, masculine, from Middle High German valz, masculine, ‘fold, joint’; akin to Old High German anafalz, ‘anvil,’ Anglo-Saxon anfilt, English anvil, Dutch anbeeld, ‘anvil’ (see Amboß). The cognates are undoubtedly connected with falten; Middle High German valz may have been *falti in Gothic, which would probably represent falt-ti, pltni- (compare schnitzen from schneiden). — Falz, see Balz.