Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† Ĕpŏna, ae, f. [from equus; cf. Gr. ἵππος; but referred to root ap- of apo by Fick, Wörterb. p. 425], the protecting goddess of horses, asses, etc., Tert. ad Nat. 1, 11; id. Apol. 16; Juv. 8, 157; Prud. Apoth. 197; App. M. 3, p. 141; Inscr. Orell. 402; 1792 sq.