Lewis & Short

in-dŭbĭtātus, a, um, adj., undoubted, without doubt, certain, sure (post-Aug.): in iis ero, quae indubitata sunt, brevior, Quint. 9, 4, 2: litterarum inter se conjunctio, id. 1, 1, 31: spes, Plin. 31, 3, 27, § 45: indubitatum est, id. 23, 1, 21, § 36: juris est, Dig. 42, 1, 49.
Comp.: illius aestatis fluxus indubitatior est, Dig. 43, 13, 1, § 8.
Advv.: in-dŭbĭtātē and indŭbĭtātō, undoubtedly.

        1. (α) Form indubitate (class.); sup., Oros. 3, 23 fin. (a false read. ap. Liv. 33, 40, 5; Vell. 2, 60, 4).
        2. * (β) Form indubitato, Tert. adv. Marc. 1, 9.