Lewis & Short

ad-dŭbĭto, āvi, ātum, 1, v. n. and a., pr., to incline to doubt, to begin to doubt (in Cic. several times, but never in his orations).

  1. I. To be in doubt, to doubt; constr.
          1. (α) With de or in aliqua re: de quo Panaetium addubitare dicebant, Cic. N. D. 2, 46, 118: de legatis paululum addubitatum est, Liv. 2, 4: in his addubitare turpissimum est, Cic. Off. 3, 4, 18.
          2. (β) With pron., or num, an, etc.: ut addubitet, quid potius dicat, Cic. Or. 40: addubitavi, num a Volumnio senatore esset, id. Fam. 7, 32: an hoc inhonestum necne sit, addubites, Hor. S. 1, 4, 124; so Liv. 8, 10; cf. Drak. ad Liv. 2, 4, 7: illud addubitat, utrum, etc., Nep. Con. 5, 4 (acc. to Br. ad h. l.: to leave it undecided; cf. with dubitare, Cic. N. D. 1, 1).
          3. (γ) With acc., to be doubtful of a thing, to call in question: si plus adipiscare, re explicata, boni, quam addubitata mali, Cic. Off. 1, 24, 83; so id. Div. 1, 47, 105.
          4. (δ) With inf., to hesitate: aptare lacertos addubitat, Sil. 14, 358.
            (ε) Absol.: eos ipsos addubitare coget doctissimorum hominum tanta dissentio, Cic. N. D. 1, 6, 14; Liv. 10, 19, 13; Plin. Ep. 2, 19, 1.