Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
impaenĭtens (inp-), entis, adj. [2. inpaenitens], not repenting, impenitent (late Lat.): cor, Hier. in. Iesai. 12, 40, 27; Vulg. Rom. 2, 5.