Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. suc-cŭbo (subc-), āre, v. n., to lie under (very rare): grabatulo succubans, App. M. 1, p. 107, 39: alveum, id. ib. 9, p. 229, 30.
2. suc-cŭbo (subc-), ōnis, m. [cubo], one who lies under; hence, a lecher, Titin. ap. Non. 224, 22 (but Com. Fragm. v. 92 Rib. reads: quam arbitrer Illarum subcuboneam esse, i. e. succubam).