Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
per-sĕco, cui, ctum, 1, v. a., to cut up, exlirpate; to cut out, excise; trop.: vitium, Liv. 40, 19 fin.: rei publicae vomicas, Auct. ap. Quint. 8, 6, 15: rerum naturas, to dissect, lay bare the secrets of nature, Cic. Ac. 2, 39, 122. (For perseca, Cic. Att. 13, 23 fin., read persece; v. persequor, I. fin.)