Where does “cuishlinit” come from?

cuishlinit (Manx) comes from Manx cuishlin, from Middle Irish cuisle, from Old Irish cusle.

cuishlinit (Manx): veined

Definitions

Step	Language	Word	Meaning
1	Manx	cuishlin	vein
2	Middle Irish	cuisle	pipe, tube
3	Old Irish	cusle	—

cuishlinit — Etymology, Origin & Word History | Etymology Explorer