The Oxford English Dictionary gives no definition of Ta’ziyya.
The Ta’ziya is the commemoration of the events of the Battle of Karbala in 680 CE, when Hussein ibn Ali and his followers were martyred by the forces of the second Umayyad caliph, Yazid I.
Term Variants: 'Aza, Ta'ziyya, Taziya, Taziyah, Taziyeh
The term Ta’ziyya should not be used without an explanation as to its meaning.
Primarily done by Shia Muslims, this may involve a re-enactment or passion play, a poem with the involvement of the audience (often different for different cultures) and / or a scholar recollecting part of the history of that event. It is typically performed by Shi’a Muslims in the first ten days of Muharram, leading up to the anniversary of the martyrdom of Hussein on the tenth day of the month (‘Ashura), but can also take place on the days approaching the 40th day (Arba’een) following the day of 10th day of Muharram (‘Ashura’).
See also: Muharram, Karbala