Mithra (Proto-Indo-Iranian, nominative *Mitras) was an important Indo-Iranian divinity. Following the prehistoric cultural split of Indo-Aryan and Iranian cultures, names descended from *mitra were used for the following religious entities:
Mitra (Sanskrit Mitrá-, Mitráḥ), a deity who appears frequently in the ancient Sanskrit text of the Rigveda.
Mithra (Avestan Miθra-, Miθrō), a yazata mentioned in the Zoroastrian sacred scripture of the Avesta, whose New Persian equivalent is Mīhr / Mehr .
Mithras, the principal figure of the Greco-Roman religion of Mithraism.
Both Vedic Mitra and Avestan Mithra derive from an Indo-Iranian common noun *mitra-, generally reconstructed to have meant “covenant, treaty, agreement, promise.” This meaning is preserved in Avestan miθra “covenant.” In Sanskrit and modern Indo-Aryan languages, mitra means “friend,” one of the aspects of binding and alliance
The Indo-Iranian reconstruction is attributed to Christian Bartholomae, and was subsequently refined by A. Meillet (1907), who suggested derivation from the Proto-Indo-European root *mei “to exchange.”
A suggested alternative derivation was *meh “to measure” (Gray 1929). Pokorny (IEW 1959) refined Meillet’s *mei as “to bind.” Combining the root *mei with the “tool suffix” -tra- “that which [causes] …” (also found in man-tra-, “that which causes to think”), then literally means “that which binds,” and thus “covenant, treaty, agreement, promise, oath” etc. Pokorny’s interpretation also supports “to fasten, strengthen”, which may be found in Latin moenia “city wall, fortification”, and in an antonymic form, Old English (ge)maere “border, boundary-post”.
Meillet and Pokorny’s “contract” did however have its detractors. Lentz (1964, 1970) refused to accept abstract “contract” for so exalted a divinity and preferred the more religious “piety.” Because present-day Sanskrit mitra means “friend,” and New Persian mihr means “love” or “friendship,” Gonda (1972, 1973) insisted on a Vedic meaning of “friend, friendship,” not “contract”.
Meillet’s analysis also “rectified earlier interpretations” that suggested that the Indo-Iranian common noun *mitra- had anything to do with the light or the sun. When H. Lommel suggested that such an association was implied in the Younger Avesta (>6th c. BCE), that too was conclusively dismissed. Today, it is certain that “(al)though Miθra is closely associated with the sun in the Avesta, he is not the sun” and “Vedic Mitra is not either.”
Old Persian Mitra or Miθra – both only attested in a handful of 4th century BCE inscriptions of Artaxerxes II and III – “is generally admitted [to be] a borrowing from the Avesta,” the genuine Old Persian form being reconstructed as *Miça. (Kent initially suggested Sanskrit but later changed his mind). Middle Iranian myhr (Parthian, also in living Armenian usage) and mihr (Middle Persian), derive from Avestan Mithra.
Greek/Latin “Mithras,” the focal deity of the Greco-Roman cult of Mithraism is the nominative form of vocative Mithra. In contrast to the original Avestan meaning of “contract” or “covenant” (and still evident in post-Sassanid Middle Persian texts), the Greco-Roman Mithraists probably thought the name meant “mediator.” In Plutarch’s first century discussion of dualistic theologies, Isis and Osiris (46.7) the Greek historiographer provides the following explanation of the name in his summary of the Zoroastrian religion: Mithra is a meson (“in the middle”) between “the good Horomazdes and the evil Aremanius […] and this is why the Pérsai call the Mediator Mithra”. Zaehner attributes this false etymology to a role that Mithra (and the sun!) played in the now extinct branch of Zoroastrianism known as Zurvanism.
Vedic Mitra is a prominent deity of the Rigveda distinguished by a relationship to Varuna, the protector of rta. Together with Varuna, he counted among the Adityas, a group of solar deities, also in later Vedic texts. Vedic Mitra is the patron divinity of honesty, friendship, contracts and meetings.
The first extant record of Indo-Aryan Mitra, in the form mi-it-ra-, is in the inscribed peace treaty of c. 1400 BC between Hittites and the Hurrian kingdom of the Mitanni in the area southeast of Lake Van in Asia Minor. There Mitra appears together with four other Indo-Aryan divinities as witnesses and keepers of the pact.
in Zoroastrianism, Mithra is a member of the trinity of ahuras, protectors of asha/arta, “truth” or “[that which is] right”. Mithra’s standard appellation is “of wide pastures” suggesting omnipresence. Mithra is “truth-speaking, … with a thousand ears, … with ten thousand eyes, high, with full knowledge, strong, sleepless, and ever awake.” (Yasht 10.7). As preserver of covenants, Mithra is also protector and keeper of all aspects of interpersonal relationships, such as friendship and love.
Related to his position as protector of truth, Mithra is a judge (ratu), ensuring that individuals who break promises or are not righteous (artavan) are not admitted to paradise. As also in Indo-Iranian tradition, Mithra is associated with (the divinity of) the sun but originally distinct from it. Mithra is closely associated with the feminine yazata Aredvi Sura Anahita, the hypostasis of knowledge
The name Mithra was adopted by the Greeks and Romans as Mithras, chief figure in the mystery religion of Mithraism. At first identified with the Sun-god Helios by the Greeks, the syncretic Mithra-Helios was transformed into the figure Mithras during the 2nd century BC, probably at Pergamon. This new cult was taken to Rome around the 1st century BC and was dispersed throughout the Roman Empire. Popular among the Roman military, Mithraism was spread as far north as Hadrian’s Wall and the Germanic Limes.