Where does “martren” come from?

martren (Middle English) comes from Old French martrine, from Old Dutch marthrīn, from Old Dutch marthar — marten.

Ancestry of “martren”, step by step

Step	Language	Word	Meaning
1	Old French	martrine	marten fur
2	Old Dutch	marthrīn	of marten fur
3	Old Dutch	marthar	marten

martren — Etymology, Origin & Word History | Etymology Explorer