Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. Ĕrăsīnus, i, m., = Ἐρασῖνος, a river of Argolis, now Kephalari, Mel. 2, 3, 9; Plin. 2, 103, 106, § 225; Ov. M. 15, 276; cf. Sen. N. Q. 3, 26, 3.