Lewis Short
(adjective) : ĭn-ŏpīnābĭlis, e
* Not to be supposed or expected, inconceivable: latebra,Gell. 17, 9, 18: id (dictum),id. 11, 18, 11: res,Aur. Vict. Caes. 39.
* Esp., rhet. t. t., surprising, paradoxical: infames materias, sive quis mavult dicere inopinabiles, quas Graeci ἀδόξους ὑποθέσεις appellant, veteres adorti sunt, Gell. 17, 12, 1.—Adv.: inŏpīnābĭlĭter, unexpectedly, Cassiod. Hist. Eccl. 1, 3; 8, 1.
Charlton T. Lewis, Charles Short, A Latin Dictionary