An Etymological Dictionary of the German Language/Annotated/Gulden

by Friedrich Kluge

Gulden, masculine, ‘florin,’ from the equivalent Middle High German gulden, guldîn, masculine, ‘the golden coin,’ from Middle High German guldîn, ‘golden.’ The absence of mutation from u to ü is in accordance with the practice of earlier Upper German (Suabian Gülden).