Where does “Vianoce” come from?

Vianoce (Slovak) comes from German weihnachten, from Middle High German wīhenahten, from Middle High German ze den wīhen nahten — in the holy nights.

Ancestry of “Vianoce”, step by step

Step	Language	Word	Meaning
1	German	weihnachten	To be nearly Christmas; to have a Christmassy...
2	Middle High German	wīhenahten	Christmas
3	Middle High German	ze den wīhen nahten	in the holy nights

Vianoce — Etymology, Origin & Word History | Etymology Explorer