Lewis & Short

crēdĭbĭlis, e, adj. [credo], worthy of belief, credible: credibile est quod sine ullo teste auditoris opinione firmatur, Cic. Inv. 1, 30, 48 (class. in prose and poetry): tametsi verissimum esse intellegebam, tamen credibile fore non arbitrabar, id. Verr. 2, 5, 61, § 158: narrationes, id. Or. 36, 124; cf. Quint. 4, 2, 52: imago rerum, id. 4, 2, 123: ratio, id. 5, 12, 13: suspicio, id. 9, 2, 90 et saep.: magnum narras, vix credibile, * Hor. S. 1, 9, 52; cf.: vix credibile dictu, Curt. 5, 13, 22: credibile est, with acc. and inf., Quint. 2, 3, 5; 5, 6, 2; 5, 10, 19 al.: credibili fortior illa fuit, Ov. F. 3, 618; cf. id. Tr. 1, 5, 49: aliquid credibile facere, Quint. 4, 2, 47; 4, 2, 110; 9, 1, 19; Just. 5, 5, 7: animo tyranni credibile judicium facere, Liv. 24, 5, 13.
Comp., Quint. 4, 2, 124; 6, 3, 4.
Adv.: crēdĭbĭlĭter, credibly, Cic. Deiot. 6, 17; Quint. 2, 15, 36; 3, 11, 1 al.