Where does “helse” come from?

helse (Old Danish) comes from Old Norse heilsa, from Proto-Germanic hailisōną, from Proto-Germanic hailaz, from Proto-Indo-European *kéh₂ilos.

Ancestry of “helse”, step by step

Step	Language	Word	Meaning
1	Old Norse	heilsa	health
2	Proto-Germanic	hailisōną	to greet; salute; to inquire; beseech
3	Proto-Germanic	hailaz	whole, unbroken, intact; entire, complete; hale,...
4	Proto-Indo-European	*kéh₂ilos	—

helse — Etymology, Origin & Word History | Etymology Explorer