Where does “mitra” come from?

mitra (Polish) comes from Sanskrit मित्र, from Proto-Indo-Aryan mitrás, from Proto-Indo-Iranian mitrás, from Proto-Indo-European mēy- — soft, tender, dear.

mitra (Polish): mitre

Definitions

mitre

Ancestry of “mitra”, step by step

mitra traces back through two separate lines of ancestry.

via Sanskrit मित्र

Step	Language	Word	Meaning
1	Sanskrit	मित्र	a friend, companion, associate; the sun;...
2	Proto-Indo-Aryan	mitrás	friend
3	Proto-Indo-Iranian	mitrás	covenant; treaty; agreement
4	Proto-Indo-European	mēy-	soft, tender, dear

via Latin mītra

Step	Language	Word	Meaning
1	Latin	mītra	turban
2	Ancient Greek	μίτρα	A metal guard worn round the waist; A maiden's...
3	Proto-Indo-European	mey-	to strengthen; to bind; to change, exchange

Every word from Proto-Indo-European mēy- →Every word from Proto-Indo-Iranian mitrás →Every word from Proto-Indo-Aryan mitrás →