PäritoluDerived from tantsima, or borrowed from Middle Low German dans, danz. The borrowing theory is more unlikely because of the -u- genitive and partitive.
Vormidtantsu(genitive) · tantsu(partitive) · tants(nominative, singular) · tantsud(nominative, plural) · tants(accusative, nominative, singular) · tantsud(accusative, nominative, plural) · tantsu(accusative, genitive, singular) · tantsud(accusative, genitive, plural) · tantsu(genitive, singular) · tantsude(genitive, plural) · tantsu(partitive, singular) · tantse(partitive, plural) · tantsusid(partitive, plural) · tantsu(illative, singular) · tantsusse(illative, singular) · tantsudesse(illative, plural) · tantsesse(illative, plural) · tantsus(inessive, singular) · tantsudes(inessive, plural) · tantses(inessive, plural)
Allikas: Wiktionary