Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
serrātus, a, um, adj. [serra], sawshaped, serrated (post-Aug.): dentes, Plin. 11, 37, 61, § 160: folia herbae, id. 25, 8, 46, § 84; cf. ambitus (foliorum), id. 25, 6, 30, § 66: spinae, id. 9, 59, 85, § 182: compages (ossium capitis), id. 11, 37, 48, § 132: morsus (anseris), Petr. 136, 4.
As subst.: serrā-ti, ōrum (sc. nummi), silver coins notched on the edge, Tac. G. 5 fin.; cf. Eckh. Doctr. Num. 5, p. 94 sq.