c.1300, "a payment for services rendered," also in Middle English "a pledge of security" (mid-14c.), from Old North French wage (Old French guage) "pledge," from Frankish *wadja- (cf. Old English wedd, Gothic wadi "pledge"); see wed. Modern French cognate gages (plural) means "wages of a domestic," one of a plethora of French words for different classes, e.g. traitement (university professor), paye, salaire (workman), solde (soldier), récompense, prix. The Old English word was lean, related to loan and representing the usual Germanic form (cf. Gothic laun, Dutch loon, German lohn).
early 14c., "to pledge, deposit as a pledge," from Old North French wagier (Old French gagier), from wage (see wage (n.)). Meaning "to carry on" (of war, etc.) is attested from mid-15c., probably from earlier sense of "to offer as a gage of battle" (early 15c.). Related: Waged; waging.