Zoroastrianism n. : The religious system of Zoroaster, the legislator and prophet of the ancient Persians, which was the national faith of Persia; mazdeism. The system presupposes a good spirit (Ormuzd) and an opposing evil spirit (Ahriman). Cf. Fire worship, under Fire, and Parsee.

Example:
How did Zoroastrianism influence Iranian art in ancient times?

Taxonomy
Zoroastrian, Zoroastrianism, Iranian, religion, Ahura Mazda, Parsis, texts, Muslim, Sassanid, Boyce, Yasna, druj, Islam, faith, influence, tradition, non-Muslims, Middle Persian.

Defination from the web:
Zoroastrianism, the religion and philosophy based on the teachings ascribed to the prophet Zoroaster.