Where does “*snāmus” come from?

*snāmus (Proto-Celtic) comes from Proto-Indo-European (s)neh₂- — to swim; to float.

Ancestry of “*snāmus”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	(s)neh₂-	to swim; to float

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