Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† 1. lygos, i, f., = λύγος, a plant, the chaste tree, agnus castus, Abraham’s balm (in late Lat. vitex), Plin. 24, 9, 38, § 59.
2. Lygos, i, f., = Λύγος, an ancient name of Byzantium: oppidum Byzantium … antea Lygos dictum, Plin. 4, 11, 18, § 46; Aus. de Clar. Urb. Carm. 1, 14.