Introduction
Ameretat, "Immortality" or "Undying-ness" (later Amordad), is one of the six Amesha Spentas, personifying deathlessness and eternal life, and traditionally associated with plants and vegetation.
The Amesha Spentas ("Bounteous Immortals") are six (or, counting Ahura Mazda himself as their head, seven) divine beings who represent and administer aspects of Ahura Mazda's good creation. Zoroastrian theology generally treats them as emanations or aspects of Ahura Mazda's own nature rather than as separate offspring in an ordinary genealogical sense, and each is opposed by one of the six chief daevas in Zoroastrian dualism.
Immortality and plants
Ameretat represents the final reward of the righteous: the immortality that will be granted to all at the resurrection following Frashokereti, the renovation of the world. Her association with plants reflects the ancient symbolic link between vegetation, renewal and the promise of life continuing beyond death.
Pairing with Haurvatat
Ameretat is closely paired with Haurvatat, "Wholeness/Health"; the two Amesha Spentas together represent a complete arc from bodily well-being to ultimate immortality, and both are especially invoked in the Zoroastrian ritual use of plants and the sacred haoma drink.
Opposing daeva
Ameretat is opposed by Zairicha, one of the six chief daevas, associated with poison, decay and death, the direct inversion of her own domain of undying life.