Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Clūsĭus, ii, m. [cludo = claudo], a cognomen of Janus, whose temple was closed in peace (opp. Patulcius, when open during war), Ov. F. 1, 130; cf. Clusivius, Macr. S. 1, 9.