Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Caeso (Kaeso, v. the letter K), ōnis, m. [a caeso matris utero dictus, Plin. 7, 9, 7, § 47; cf. Paul. ex Fest. p. 57 Müll.; Isid. Orig. 9, 3, 12, and v. Caesar init.], a Roman cognomen in the gens Fabia, Liv. 2, 43, 2; 2, 48, 3 and 4; 3, 11, 6 sq. et saep.