Easton's Bible Dictionary (1897)
Probably a poetic or prolonged name of the land of Cush, the Arabian Cush (Hab. 3:7). ); but incorrectly, for the empire of Assyria was not yet founded. He held Israel in bondage for eight years.
Smith's Bible Dictionary (1863)
(blackness), (Habakkuk 3:7) possibly the same as Cushan-rishathaim (Authorized Version Chushan-) king of Mesopotamia.
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
CU'SHAN. Hab 3:7. Perhaps the same as Cush, though some think it refers to the king Chushan-rishathaim.