Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
perpessīcĭus or -tĭus, a, um, adj. [perpetior], that can endure much, that has endured much, patient, enduring (postAug.): etiam a duro et perpessicio confessionem accipit, Sen. Ep. 53, 6: Socrates perpessicius senex, id. ib. 104, 27.