French word mou comes from Proto-Indo-European *mol(w)ə-

Detailed word origin of mou

Dictionary entry	Language	Definition
*mol(w)ə-	Proto-Indo-European (ine-pro)
*(h₂)ml̥dus	Proto-Indo-European (ine-pro)
mollis	Latin (lat)	(New Latin) Used as a species epithet.. Mild, tender. Pliant, flexible, supple. Soft, delicate to the touch. Tender, weak.
mol	Old French (fro)
mou	French (fra)	(informal) pansy, spineless. Soft, pliable Lungs, lights (of a slaughtered animal).