Easton’s Bible Dictionary

Bay : denotes the estuary of the Dead Sea at the mouth of the Jordan (Joshua 15:5; 18:19), also the southern extremity of the same sea (Joshua 15:2). The same Hebrew word is rendered "tongue" in Isaiah 11:15, where it is used with reference to the forked mouths of the Nile.

Bay in Zechariah 6:3,7 denotes the colour of horses, but the original Hebrew means strong, and is here used rather to describe the horses as fleet or spirited.