from Wiktionary, Creative Commons Attribution/Share-Alike License
- proper n. The emigration of Muhammad and his followers from Mecca to Medina in 622 CE to escape persecution.
- proper n. The beginning of the Muslim era, equivalent to July 16, 622, by the Julian calendar of the day.
From Medieval Latin Hejira, from Arabic هجرة (híjra, "departure, exodus"), referring to Muhammad’s flight from Mecca to Medina in 622 CE; from the verb هجر (hájara, "to emigrate, to abandon"). (Wiktionary)