Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
magnănĭmus, a, um, adj. [magnus, animus], great-souled, magnanimous (rare but class.): viri fortes, magnanimi, Cic. Off. 1, 19, 63; id. Tusc. 4, 28, 61; Juba, Ov. F. 4, 380: heroës, Verg. A. 6, 649: Acragas, magnanimūm quondam generator equorum, high-spirited, mettlesome, id. ib. 3, 704: liberale atque magnanimum factum, highsouled, magnanimous, Gell. 6 (7), 19, 1.