Where does “dwygeill” come from?

dwygeill (Middle Welsh) comes from Middle Welsh keill, from Proto-Brythonic *köll, from Latin cōleus, from Ancient Greek κολεός, from Proto-Indo-European ḱel- — to cover; to incline.

Ancestry of “dwygeill”, step by step

Step	Language	Word	Meaning
1	Middle Welsh	keill	testicle
2	Proto-Brythonic	*köll	testicle
3	Latin	cōleus	sack (scrotum or testicles)
4	Ancient Greek	κολεός	a sword-sheath, a scabbard; a cinerary urn; a...
5	Proto-Indo-European	ḱel-	to cover; to incline

Every word from Proto-Indo-European ḱel- →Every word from Ancient Greek κολεός →Every word from Latin cōleus →