Persian god of light, 1550s, from Latin, from Greek Mithras, from Avestan Mithra-, from Indo-Iranian *mitram "contract," whence *mitras "contractual partner, friend," conceptualized as a god, or, according to Kent, first the epithet of a divinity and eventually his name; from PIE root *mei- "to bind" (see mitre). Related to Sanskrit Mitrah, a Vedic deity associated with Varuna. "His name is one of the earliest Indic words we possess, being found in clay tablets from Anatolia dating to about 1500 B.C." [Calvert Watkins, "Dictionary of Indo-European Roots," 2000]. Related: Mithraic; Mithraism.