Where does “*kersos” come from?

*kersos (Proto-Celtic) comes from Proto-Indo-European (s)ḱer- — dung, manure, filth; manure, dung, filth.

Ancestry of “*kersos”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	(s)ḱer-	dung, manure, filth; manure, dung, filth

*kersos — Etymology, Origin & Word History | Etymology Explorer