Where does “-lauss” come from?

-lauss (Old Norse) comes from Proto-Germanic -lausaz, from Proto-Germanic lausaz, from Proto-Indo-European lewH- — louse.

Ancestry of “-lauss”, step by step

Step	Language	Word	Meaning
1	Proto-Germanic	-lausaz	-less, lacking, devoid of
2	Proto-Germanic	lausaz	loose, free; empty, devoid; false, untrue
3	Proto-Indo-European	lewH-	louse

-lauss — Etymology, Origin & Word History | Etymology Explorer