ʕśr / Semitic roots

Common Semitic *ʕaśr-, ten.

Ashura, from Arabic ʕāšūrāʔ, the tenth of Muharram kept as a fast day by Arabs in pre-Islamic times, Ashura, ultimately (probably via Aramaic *ʕāsorā) from Hebrew ʕāśôr, a set of ten (days, etc.), decade (used in Leviticus to specify the date of Yom Kippur, the tenth of Tishri), from ʕeśer, ten.