Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
cĕrĕbellum, i, n. dim. [cerebrum], a small brain, Cels. 2, 18; Plin. 29, 5, 32, § 100; 30, 13, 38, § 112; * Suet. Vit. 13.
Figuratively, Petr. 76, 1.