Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Ĕrīnys (or, less correctly, Erinnys; cf. Wagner ad Verg. A. 2, 337), yos, f.,  =  Ἐριννύς (Ἐρινύς), 
- I. one of the Furies, Verg. A. 7, 447; 570; Ov. M. 1, 241; 4, 490; 11, 14 et saep.
Acc. Erinyn, Ov. M. 1, 725.
In plur.: Erinyes, the Furies, Prop. 2, 20, 29 (3, 13, 29 M.); Ov. H. 11, 103.
Acc. Erinyas, Stat. Th. 11, 345. 
- II.  Transf. 
 
- A.  Of Helen: Trojae patriae communis Erinys, the scourge, curse, Verg. A. 2, 573.
 
- B.  Appellatively, fury, frenzy, madness  =  furor, Verg. A. 2, 337: civilis, i. e. civil war, Luc. 4, 187.