Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
com-pascŭus, a, um, adj., of or pertaining to common pasturage: ager, a common pasture, Cic. Top. 3, 12; Lex Thor.; Inscr. Orell. 3121; cf. Paul. ex Fest. p. 40, 1 Müll.: jus compascui, Dig. 8, 5, 20; cf. Quint. 5, 10, 85.