Merathaim
Easton's Bible Dictionary 1897
Double rebellion, probably a symbolical name given to Babylon (Jer. 50:21), denoting rebellion exceeding that of other nations.
Smith's Bible Dictionary 1863
(double rebellion), The land of, alluding to the country of the Chaldeans, and to the double captivity which it had inflicted on the nation of Israel. (Jeremiah 50:21)
International Standard Bible Encyclopedia 1915
mer-a-tha'-im (merathayim "double rebellion"): A name used for Babylon in Jer 50:21. According to Delitzsch it may be equivalent to the Babylonian Marratun, i.e. land by the nar Marratu, "the bitter river" (Persian Gulf) = Southern Babylonia (OHL, under the word).