early 15c., from M.Fr. engagier, from O.Fr. en gage "under pledge," from en "make" + gage "pledge," through Frankish from P.Gmc. *wadiare "pledge" (showing the common evolution of Gmc. -w- to Fr. -g-; cf. Guillaume from Wilhelm). Specific sense of "promise to marry" first recorded 1727. Related: Engaged.