Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† mĭsy, yos (in the gen. also misys, Scrib. Comp. 34; and, misy, Cels. 6, 7, 2; 5, 19, 15; Veg. 6, 16, 1), n., = μίσυ.