Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
sĕris, ĭdis, f., = σέρις, a kind of endive, Plin. 20, 8, 32, § 76; Varr. R. R. 3, 10, 5 (in Col. 8, 14, 2, written as Greek).