Zarathushtra Spitama, more commonly known as Zoroaster, was an Iranian religious reformer who challenged the tenets of the contemporary Ancient Iranian religion, becoming the spiritual founder of Zoroastrianism. In the oldest Zoroastrian scriptures, the Gathas, which he is traditionally believed to have authored, he is described as a preacher and a poet-prophet. Some have claimed, with much scholarly controversy, to find his influence in Heraclitus, Plato, Pythagoras, and, perhaps less controversially, in the Abrahamic religions, including Judaism, Christianity, and Islam, particularly through concepts of cosmic dualism and personal morality.
He spoke an Old Iranian language, named Avestan by scholars after the corpus of Zoroastrian religious texts written in that language. Based on this, it is tentative to place his homeland somewhere in the eastern regions of the Greater Iran (possibly Bactra, now in modern-day Afghanistan). His life is traditionally dated to some time around the 7th and 6th centuries BC; though most scholars, using linguistic and socio-cultural evidence, suggest a dating even further back to the end of the 2nd and the beginning of the 1st millennium BC. Zoroaster is credited with authorship of the Gathas as well as the , a series of hymns composed in Old Avestan that cover core Zoroastrian beliefs. Little is known about Zoroaster; most of his life is known only from these scant texts. as used in Xanthus's (Fragment 32) and in Plato's First Alcibiades (122a1). This form appears subsequently in the Latin , and, in later Greek orthographies, as . The Greek form of the name appears to be based on a phonetic adaptation or semantic substitution of Avestan with the Greek (literally 'undiluted') and the BMAC substrate with .
In Avestan, is generally accepted to derive from an Old Iranian . The second component of the name () is thought to be the Indo-Iranian root for 'camel', with the entire name meaning 'he who can manage camels'. Reconstructions from later Iranian languages—particularly from the Middle Persian (300 BC) , which is the form that the name took in the 9th- to 12th-century Zoroastrian texts—suggest that might be a zero-grade form of . Subject then to whether derives from or from , several interpretations have been proposed.
If is the original form, it may mean 'with old/aging camels', related to Avestic
- 'with angry/furious camels': from Avestan , 'angry, furious'.
- 'who is driving camels' or 'who is fostering/cherishing camels': related to Avestan , 'to drag'.
- Mayrhofer (1977) proposed an etymology of 'who is desiring camels' or 'longing for camels' and related to Vedic Sanskrit , 'to like', and perhaps (though ambiguous) also to Avestan .
The interpretation of the () in the Avestan was for a time itself subjected to heated debate because the is an irregular development: as a rule, (a first element that ends in a dental consonant) should have Avestan or as a development from it. Why this is not so for has not yet been determined. Notwithstanding the phonetic irregularity, that Avestan with its was linguistically an actual form is shown by later attestations reflecting the same basis.
In Middle Persian, the name is , in Parthian , in Manichaean Middle Persian ,
Classical scholarship
Classical scholarship in the 6th to 4th century BC believed he existed 6,000 years before Xerxes I's invasion of Greece in 480 BC (Xanthus, Eudoxus, Aristotle, Hermippus), which is a possible misunderstanding of the Zoroastrian four cycles of 3,000 years (i.e. 12,000 years). This belief is recorded by Diogenes Laërtius, and variant readings could place it 600 years before Xerxes I, somewhere before 1000 BC. According to Pliny the Elder, there were two Zoroasters. The first lived thousands of years ago, while the second accompanied Xerxes I in the invasion of Greece in 480 BC.
Zoroastrian and Muslim scholarship
Some later pseudo-historical and Zoroastrian sources (the , which references a date "258 years before Alexander") place Zoroaster in the 6th century BC,