Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
3. Ănas, ae, m., a river in Spain, now Guadiana (Arab., i. e. Wadi-Ana, = river Anas), Caes. B. C. 1, 38; Plin. 3, 1, 3, § 3; 4, 22, 35, § 116; Mel. 2, 6; 3, 1; cf. Mann. Hispan. 325.