Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† Cătăgĕlăsĭmus, a, um, adj., = καταγελάσιμος, serving for ridicule; subst. m., a banterer, jeerer, in a pun with Gelasimus, the name of a parasite: nolo ex Gelasimo fleri te Catagelasimum, Plaut. Stich. 4, 2, 50.