engage: [15] Vulgar Latin had a noun *wadium ‘pledge’ (it came from Germanic *wathjam, source also of English wed and wage). From it was derived a verb *wadiāre ‘pledge’, which formed the basis of a compound *inwadiāre. Germanic w became g in French (hence French Guillaume for William), so the Old French descendant of *inwadiāre was engager, acquired by English as engage. (The superficially similar gauge [15] is probably not related, although it is not known for certain what its ultimate source is.) => wage, wed[engage etymology, engage origin, 英语词源]