WordNet (r) 3.0 (2006):

East Sea
    n 1: an arm of the Pacific between China and Japan [syn: Sea of
         Japan, East Sea]

Easton's 1897 Bible Dictionary:

East sea
   (Joel 2:20; Ezek. 47:18), the Dead Sea, which lay on the east
   side of the Holy Land. The Mediterranean, which lay on the west,
   was hence called the "great sea for the west border" (Num.
   34:6).