Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
* impī̆grĭtas (inp-), ātis, f. [impiger], activity, indefatigableness: viri fortissimi fortitudinis, impigritatis, patientiae, Cic. Rep. 3, 28, 40 (ap. Non. 125, 22).