Daleth
From BiblePortal Wikipedia
Hastings' Dictionary of the Bible [1]
Daleth . Fourth letter of Heb. alphabet, and as such used in the 119th Psalm to designate the 4th part, each verse of which begins with this letter.
International Standard Bible Encyclopedia [2]
da´leth ( דּ , ד ): The 4th letter of the Hebrew alphabet, and as such used in Ps 119 to designate the 4th section; transliterated in this Encyclopedia with the dagesh as d , and, without, as dh ( = th in "the"). It came also to be used for the number four (4), and with the dieresis for 4,000. With the apostrophe it is sometimes used as abbreviation for the tetragrammaton. For name, etc., see Alphabet .
