Strong's #4850: Mrathayim (pronounced mer-aw-thah'-yim)
 dual of 4751 feminine; double bitterness; Merathajim, an epithet of Babylon:--Merathaim.
Brown-Driver-Briggs Hebrew Lexicon:
 
  merâthayim 
 
 Merathaim = "double rebellion" 
 1) another name for ' Babylon' 
 
  Part of Speech: noun proper feminine
Relation: dual of H4751
Usage:
This word is used 1 times:
Jeremiah 50:21: "Go up against the land  of Merathaim, even against it, and against the inhabitants of Pekod:"