Where does “unrhyw un” come from?

unrhyw un (Welsh) comes from Welsh unrhyw, from Welsh un, from Middle Welsh un, from Proto-Brythonic ʉn, from Proto-Celtic oinos, from Proto-Indo-European óynos — one; single.

unrhyw un (Welsh): anyone, anybody

Definitions

anyone, anybody

Ancestry of “unrhyw un”, step by step

Step	Language	Word	Meaning
1	Welsh	unrhyw	any
2	Welsh	un	only; one; one, individual
3	Middle Welsh	un	one
4	Proto-Brythonic	ʉn	one
5	Proto-Celtic	oinos	one
6	Proto-Indo-European	óynos	one; single

Every word from Proto-Indo-European óynos →Every word from Proto-Celtic oinos →Every word from Proto-Brythonic ʉn →