SIN.  The Moon-god.  He was the father of the younger Ishtar.  He was a favourite deity of the Cushite kings of the early Babylonians, and the principal object of worship in the city of Ur.  In the later periods of Assyrian mythology he became a divinity of only secondary importance.  His titles were "Lord of Crowns," "Maker of Brightness," and "Lord of the City of Ur."
    SIN.  A Sabaean deity.  The analogue of the Chaldean divinity of the same name. (An Archaic Dictionary, Cooper, 1876).

    The worship of Sin is particularly associated with Harran.  But after the time of Hammurabi, Nannar and Sin became identical.  Nannar was the "illuminator," and this character was transferred to Sin.  Sin was represented as being the father of the goddess Ishtar (q.v.).  As in the case of Marduk (q.v.), the child seems in course of time to a large extent to have taken the place of the parent.  When, moreover, the lunar cycle was accommodated to the movements of the sun, Shamash naturally became more prominent than Sin.  The Assyrian kings refer to sin as a war-god who inspires terror.  The consort of Sin was Nin-gal.  The ship in which Sin was carried in procession was called "ship of light." (An Encyclopedia of Religions, Canney, 1921)

    Sin, the Moon-god, ranked next to Beltis in Assyrian mythology, and his place is thus either fifth or sixth in the full lists according to Beltis is, or is not, inserted.  His worship in the time of the early empire appears from the invocation of Tiglath-Pileser I., where he occurs in the third place, between Bel and Shamash.  His emblem, the crescent, was worn by Asshur-izir-pal, and is found wherever divine symbols are inscribed over their effigies by the Assyrian kings.  There is no sign which is more frequent on the cylinder-seals, whether Babylonian or Assyrian, and it would thus seem that Sin was among the most popular of Assyria's deities.  His name occurs sometimes, though not so frequently as some others, in the appellations of important personages, as e.g. in that of Sennacherib, which is explained to mean "Sin multiplies brethren."  Sargon, who thus named one of the his sons, appears to have been specially attached to the worship of Sin, to whom, in conjunction with Shamash, he built a temple at Khorsabad, and to whom he assigned the second place among the tutelary deities of his city. 
    The Assyrian monarchs appear to have had a curious belief in the special antiquity of the Moon-god.  When they wished to mark a very remote period, they used the expression "from the origin of the god Sin."  This is perhaps a trace of the ancient connection of Assyria with Babylonia, where the earliest capital, Ur, was under the Moon-god's protection, and the most primeval temple was dedicated to his honour.
    Only two temples are known to have been erected to Sin in Assyria.  One is that already mentioned as dedicated by Sargon at Bit-Sargina (Khorsabad) to the Sun and Moon in conjunction.  The other was at Calah, and in that Sin had no associate. (The Five Great Monarchies of the Ancient Eastern World, Rawlinson, 1871)