Where does “veineux” come from?

veineux (Middle French) comes from Latin venosus, from Latin -ōsus, from Old Latin -ōssus.

Ancestry of “veineux”, step by step

Step	Language	Word	Meaning
1	Latin	venosus	full of veins, venous; dry, meagre
2	Latin	-ōsus	ose, -ous, -ful (full of or overly prone to)
3	Old Latin	-ōssus	—