Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Sēmo, ōnis, m. [probably from sēmen], an ancient god that presided over the crops: SEMVNIS ALTERNEI ADVOCAPIT CONCTOS, song of the Fratres Arvales, Inscr. Orell. 2270.
As an epithet of Sancus, Ov. F. 6, 214; Liv. 8, 20; Inscr. Orell. 1860; 6999.