Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Sōsĭa, ae, m., the name of a servant, in Plaut. Am. 1, 1, 209, and Ter. And 1, 1, 1; cf. Auct. Her. 4, 50, 63.
The same, called Sōsĭas, Aus. Ephem. Egress. 9.