Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Parthēni or Parthīni, ōrum, m., = Παρθεινοί or Παρθινοί,
3. Parthus, i, f., a city in Illyria, near Dyrrachium; hence, Parthīni (Par-thēni), ōrum, m., the inhabitants of Parthus, Parthinians, Mel. 2, 3, 11; Plin. 3, 22, 26, § 143; Cic. Pis. 40, 96; Caes. B. C. 3, 11; 41; 42; Liv. 29, 12; 33, 34 fin.; Fasti Capitol. ap. Grut. 297; Marin. Frat. Arv. p. 607.
In sing.: Parthīnus, i, m.