The word 'tryst' originates from the Old French 'triste' or 'tristre', meaning a hunting station or an appointed waiting place. This Old French term is believed to be derived from a Scandinavian source, such as Old Norse 'treysta', meaning 'to trust, rely on', which itself is related to the Old English 'trēowe' (faith, pledge). The semantic evolution moved from a neutral 'appointed meeting place' (as for hunters) to specifically denote a pre-arranged, often secret, rendezvous. By the late Middle English period, its association with romantic or clandestine meetings became firmly established, linking the concept of a 'trusted' agreement to a private encounter.

The word is a simplex. It entered English as a whole lexical unit from Old French.