Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
septem-flŭus, a, um, adj. [fluo], sevenfold-flowing, an Ovidian epithet of the Nile (as having seven mouths): Nilus, Ov. M. 1, 422: flumina Nili, id. ib. 15, 753 (cf. the foll. art. and septemplex).