köken: From Middle Dutch gerne, gaerne, from Old Dutch *gerno, from Proto-West Germanic *gernō, from Proto-Germanic *gernô (“willingly, gladly”), an adverbial form of *gernaz (“willing”).
köken: Learned borrowing from Koine Greek εὐχαρίστως (eukharístōs, “gratefully”), with semantic loan from French avec plaisir. By surface analysis, ευχάριστος (efcháristos) + -ως (-os).
Inherited from Old French volentier, veluntiers, from Latin voluntārie (used as an adjective), derived from voluntārius. Compare with the etymologically related terms volontaire, volonté, vouloir.