Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
implŭvĭātus (inpl-), a, um, adj. [impluvium], shaped like an impluvium, i. e. four-sided, having a square border: vestis, a kind of garment worn by women, Plaut. Ep. 2, 2, 40.