Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Ămorgus or -ŏs, i, f., = Ἀμοργός, one of the Sporades in the Ægean Sea, the birthplace of the poet Simonides; under the Roman emperors, a place for the banishment of criminals; now Amorgo, Plin. 4, 12, 23, § 70; Tac. A. 4, 30; v. Mann. Gr. 734 sq.