Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
faenĕrāto (less correctly fēn-, foen-), adv. [faeneratus], with interest (Plautinian): nae illam mecastor faenerato abstulisti, Plaut. Men. 4, 2, 40: nae ille ecastor faenerato funditat, id. As. 5, 2, 52.