The first question of Fatwa no. 6951

Q 1: why is the 10th of Muharram called the Day of ‘Ashura’?

A: Because it is the tenth day [‘Ashura’ means tenth in Arabic. ed.], just as the ninth day is called Tasu‘a’.

May Allah grant us success! May peace and blessings be upon our Prophet, his family, and Companions!

Permanent Committee for Scholarly Research and Ifta’
Member     Chairman
`Abdullah ibn Qa`ud     `Abdul-`Aziz ibn `Abdullah ibn Baz

Source: alifta.net