Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
* magnātus, i, m., and magnas, ātis, m. [magnus], a great man, important person, magnate (post-class.): omnes magnates, Vulg. Judith, 5, 26: in conspectu magnatorum, id. Sir. 38, 3; 33, 19; Inscr. ap. Demster. ad Rosini Antiq. 2, 12: magnates, μεγιστᾶνες, Gloss.