Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
impūrātus (inp-), a, um, P. a., from impuro, not in use (for in Sen. Ep. 87, 16, the true reading is inspurcavit), morally defiled; hence, in gen., infamous, abominable, abandoned, vile (ante- and post-class.): impuratus me ille ut etiam irrideat? that vile wretch, Ter. Phorm. 4, 3, 64; 5, 7, 69: belua, as a term of reproach, Plaut. Rud. 2, 6, 59: nisi scio probiorem hanc esse quam te, impuratissime, id. ib. 3, 4, 46: impuratissima illa capita (hominum), App. M. 8, p. 221, 19.