Dey is the tenth month of the Zoroastrian calendar. Its name derives from Dadvah, meaning 'Creator', an epithet of Ahura Mazda. As with all Zoroastrian months, Dey has thirty days.
Because of its connexion with Ahura Mazda there are four name-day feasts celebrated during the month. These are
- Ohrmazd Dey — 1 Dey.
- Dey-pa-Adar Dey — 8 Dey.
- Dey-pa-Mihr Dey — 15 Dey.
- Dey-pa-Din Dey — 23 Dey.
Also the gahambar (five-day seasonal festival) of Maidyarem occurs in this month, from 16–20 Dey.
The three Zoroastrian calendars place Dey at different places in the natural year. The present corrolation with the Gregorian calendar is: