Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
impĕtrātĭo (inp-), ōnis, f. [impetro], an obtaining by request, accomplishment, Cod. Just. 2, 58, 2; Cod. Th. 11, 22, 4.
Plur.: istas impetrationes nostras nihil valere, Cic. Att. 11, 22, 1.