Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Rhamnūs, untis, f., = Ῥαμνοῦς, the northernmost town of Attica, famed for an ancient temple of Themis, and in later times for a statue of Nemesis, the mod. Ovriokastro, Plin. 4, 7, 11, § 24; 36, 5, 4, § 17; Luc. 5, 233.
Hence,