Apparently from Kuwshan and the dual of rish'ah; Cushan of double wickedness; Cushan-Rishathajim, a Mesopotamian king -- Chushan-rishathayim.
see HEBREW Kuwshan
see HEBREW rish'ah
H3573. Kushan
Rishathayim רִשְׁעָתַ֫יִם כּוּשַׁן proper name, masculine king of Aram Naharaim Judges 3:8 (twice in verse); 3:10 (twice in verse); otherwise unknown, ᵐ5 Ξουσαρσαθαιμ, ᵐ5L Ξουσανρεσαμωθ.
כּוֺשָׁרוֺת see [ כּוֺשָׁרָה] below כָּשַׁר.