Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
crētŭla, ae, f. dim. [2. creta], white clay, used for sealing, = terra sigillata, Cic. Verr. 2, 4, 26, § 58; Plin. 35, 7, 31, § 49.