Where does “ard-chuishlin” come from?

ard-chuishlin (Manx) comes from Manx cuishlin, from Middle Irish cuisle, from Old Irish cusle.

ard-chuishlin (Manx): lode, ore body

Definitions

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

ard-chuishlin — Etymology, Origin & Word History | Etymology Explorer