Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† cĕrătĭna, ae, f., = κερατίνα, the sophistical argument concerning horns (quod non perdidisti habes; cornua non perdidisti: habes igitur cornua, Gell. 18, 2, 8; cf. Sen. Ep. 45, 7), Quint. 1, 10, 5 Spald.; Front. Eloq. p. 86 Nieb.