Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
crēdŭlĭtas, ātis, f. [credulus], easiness of belief, credulity (first freq. after the Aug. per.; never in Cic.): credulitas error est magis quam culpa, Plancus ap. Cic. Fam. 10, 23, 1; Quint. 5, 3, 7; Tac. A. 2, 40; Curt. 7, 7, 8; Ov. M. 15, 498; id. P. 1, 1, 44.
Of fishes trusting themselves to the hook, Ov. M. 13, 934; 15, 101; cf. credulus.
As a person, together with Error, Ov. M. 12, 59.