Lewis & Short

trĭlinguis, e, adj. [ter-lingua].

  1. I. triple-tongued, having three tongues: ōs (Cerberi), Hor. C. 3, 11, 20: cantus (Hecates), Val. Fl. 7, 184: colla (i. e. serpentis), Prud. Cath. 3, 150.
  2. II. Speaking three tongues or languages: Massilienses (who spoke Greek, Latin, and Gallic), Varr. ap. Isid. Orig. 15, 1 fin.: Siculi (because they spoke Greek, Punic, and Latin), App. M. 11, p. 259: ego Hebraeus, Graecus, Latinus: trilinguis, Hier. in Ruf. 3, 6.