Dutch word leenheer comes from Dutch heer ((archaic) army Gentleman. Lord; master.), Dutch leen (A fief, feudal estate, nomination or other grant.)

Detailed word origin of leenheer

Dictionary entry	Language	Definition
heer	Dutch (nld)	(archaic) army Gentleman. Lord; master.
leen	Dutch (nld)	A fief, feudal estate, nomination or other grant.
leenheer	Dutch (nld)	Feudal lord, thegn.

Words with the same origin as leenheer