Where does “sarf” come from?

sarf (Middle Welsh) comes from Proto-Brythonic *sarf, from Vulgar Latin *sarpēs, from Latin serpēns, from Latin serpō, from Proto-Indo-European serp- — to creep, crawl.

Ancestry of “sarf”, step by step

Step	Language	Word	Meaning
1	Proto-Brythonic	*sarf	—
2	Vulgar Latin	*sarpēs	—
3	Latin	serpēns	A serpent, snake
4	Latin	serpō	to creep, crawl, move slowly of an animal
5	Proto-Indo-European	serp-	to creep, crawl

Words derived from “sarf”

sarff

Every word from Proto-Indo-European serp- →Every word from Latin serpō →Every word from Latin serpēns →