Where does “kobberbryllup” come from?

kobberbryllup (Danish) comes from Danish kobber, from Old Danish kopær, from Latin cūprum, from Latin cȳprium, from Ancient Greek Κύπρος, from Ancient Greek -ῐος, from Proto-Indo-European -yós — Creates adjectives from noun or verb stems.

kobberbryllup (Danish): twelve-and-a-half-year anniversary of marriage