Lewis & Short

Tălasĭo (Tălassĭo), ōnis, or Tă-lassĭus (Thăl-), ii, m., a congratulatory exclamation to a bride, in use from the time of Romulus, like the Gr. Ὑμὴν ὦ ὑμέναιε. Its meaning was unknown to the ancient writers themselves, but it was probably the name of the god of marriage, Liv. 1, 9, 12; Serv. Verg. A. 1, 651; Fest. pp. 351 and 350 Müll.; Cat. 61, 134; Mart. 1, 36, 6; 12, 42, 4; cf. Becker, Gallus, 2, p. 17 (2d ed.).
In mal. part., Mart. 12, 96, 5.