Where does “*ḷsso-s” come from?

*ḷsso-s (Proto-Celtic) comes from Proto-Indo-European *pl̥t-to-.

Ancestry of “*ḷsso-s”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	*pl̥t-to-	—

*ḷsso-s — Etymology, Origin & Word History | Etymology Explorer