Webster's Dictionary 
(1): ( n.) The writer of the passages of the Old Testament, especially those of the Pentateuch, in which the Supreme Being is styled Jehovah. See Elohist.
(2): The author of the passages of the Old Testament, esp. those of the Hexateuch, in which God is styled Yahweh, or Jehovah; the author of the Yahwistic, or Jehovistic, Prophetic Document (J); also, the document itself.
(3): ( n.) One who maintains that the vowel points of the word Jehovah, in Hebrew, are the proper vowels of that word; - opposed to adonist.
The Nuttall Encyclopedia 
The presumed author of the Jehoistic portions of the Pentateuch. See Elohist .