Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Sindŏs, i, f., a city of Scythia, on the Cimmerian Bosporus, Mel. 1, 19.
Hence, Sindŏnes, um, m., the inhabitants of Sindos, Mel. 1, 19; cf. Sindica.
Sindus, i, m., an Indian name of the river Indus, Plin. 6, 20, 23, § 71.