Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
trĭmŏdĭa, ae, f. (collat. form trĭmŏ-dĭum, ii, n., Plaut. Men. prol. 15; Plin. 33, 1, 6, § 20) [tres-modius], a vessel that contains three modii, a three-peck measure, Varr. ap. Non. 5, 18; Col. 2, 9, 9; 12, 18, 2; 12, 52, 8.