late 14c., "appointment to meet at a certain time and place," from Old French tristre "waiting place, appointed station in hunting," probably from a Scandinavian source such as Old Norse treysta "to trust, make firm" (see trust (v.)). The notion would be "place one waits trustingly." As a verb, late 14c. Related: Trysting.[tryst etymology, tryst origin, 英语词源]