Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
impūrĭtas (inp-), ātis, f. [impurus], uncleanness (in a moral sense), pollution, impurity: cum omnes impuritates pudica in domo quotidie susciperes, Cic. Phil. 2, 3, 6; sing., Vulg. Lev. 5, 3.