Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
asprētum, i, n. [asper], an uneven, rough place: ad hoc saxa erant temere jacentia, ut fit in aspretis, Liv. 9, 24, 6; 27, 18; 35, 28; 36, 15; Grat. Cyn. 241.