Reconstruction:Proto-Indo-Iranian/mitrás

Etymology
Original PII meaning is preserved in Avestan. 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. Contradicting suggestions included (Gray 1929).

Pokorny (IEW 1959) refined Meillet's *mey- as “to bind”. Combining the root *mey- with the ‘tool suffix’ -tra- "that which [causes] …" (also found e. g. in Sanskrit ), 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, and in an antonymic form, Old English.

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 means “friend”, and New Persian  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 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 —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 *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 and Latin, the focal deity of a Greco-Roman cult, 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 1st century discussion of dualistic theologies, the Greek historiographer provides the following explanation of the name in his summary of the Zoroastrian religion: Mithra is a between “the good Horomazdes and the evil Aremanius […] and this is why the Pérsai call the Mediator Mithra” (Isis and Osiris 46.7). Zaehner attributes this false etymology to a role that Mithra (and the sun!) played in the now extinct branch of Zoroastrianism known as Zurvanism.

Noun

 * 1) covenant
 * 2) treaty
 * 3) agreement
 * 4) promise