Lewis & Short

ĭn-ŏpīnus, a, um, adj., unexpected (poet. and in post-Aug. prose = in-opinatus, insperatus): quies, Verg. A. 5, 857: nova inopinave facies laborum, id. ib. 6, 104: fors, id. ib. 8, 476: visus, Ov. M. 4, 232: siccitas, Plin. Pan. 30, 2; Tac. A. 1, 68.