Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
trĭ-pĕdānĕus, a, um, adj. [ter], of three feet in measure, three-foot-: taleas, Cato, R. R. 45, 1: vites, Col. 3, 2, 2: scrobis, id. 5, 5, 2: statuae, Plin. 34, 6, 11, § 24.