Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† centaurēum or -ĭon, i, n. (access. form centaurĭa, ae, f., App. Herb. 34 and 35), = κενταύρειον and κενταύριον, centaury, a plant of two kinds: majus, Centaurea centaurium, Linn.; and minus, Gentiana centaurium, id.; Plin. 25, 6, 30, § 66: ferum, Lucr. 2, 401: tristia, id. 4, 124: Thessala, Luc. 9, 918; Verg. G. 4, 270.