The exact nature and function of the winged disk in Western Asia have been the subject of discussion and disagreement for over half a century. There is no shortage of evidence; representations are found over a very wide geographical and chronological span. However, a new monument has recently come to light in Arabia, and it affords an unparalleled context for the winged disk. This study investigates in detail the proposal made by Winnett in 1970, that the Aramaic deity ṢLM, known mainly from inscriptions in the area of N.W. Arabia around the city of Teima, is the winged disk, and analyses cuneiform sources for the cognate Akkadian god Ṣalmu. The evidence shows that Ṣalmu may indeed be a name for the winged disk in cuneiform, and there are good indications that the winged disk was an object on which oaths of loyalty were sworn to the king and probably also to the crown prince during the neo-Assyrian period. Probable references to Ṣalmu as the winged disk in personal names and in various texts dating to the late second and early first millennia B.C. are assembled. Some evidence that Hebrew 'edūṯ and late Babylonian Adēšu are West Semitic words for the winged disk is presented. In the second part of the study the title šamšī, meaning “his/your majesty”, is investigated, and evidence is presented to show that the winged disk was adopted as the visual equivalent of the verbal title šamšī, and marked both mortal kings and certain deities who could claim to be head of a pantheon in a particular city or country. The symbol, whether representing a human or divine king, proclaims the sovereign's protection under oaths of loyalty which were guaranteed by dire curses and enforced by sympathetic magic on oath-breakers.