Where does “espinus” come from?

espinus (Old French) comes from Latin spinosus, from Latin spīna, from Proto-Italic speinā, from Proto-Indo-European spēy- — to stretch; thrive; succeed.

Ancestry of “espinus”, step by step

Step	Language	Word	Meaning
1	Latin	spinosus	thorny, prickly
2	Latin	spīna	a thorn or a thorny tree or shrub, such as whitethorn, hawthorn, or blackthorn
3	Proto-Italic	speinā	thorn
4	Proto-Indo-European	spēy-	to stretch; thrive; succeed

Every word from Proto-Indo-European spēy- →Every word from Proto-Italic speinā →Every word from Latin spīna →