, the name of a religious movement founded at Baṣra, in the first half of the 2nd/8th century by Wāṣil b. ʿAṭāʾ (d. 131/748 [q.v.]), subsequently becoming one of the most important theological schools of Islam.

The origin of this term—which has the sense of “those who separate themselves, who stand aside”— remains enigmatic. According to a traditional explanation (sometimes acknowledged by the Muʿtazila themselves), the word would have been applied to Wāṣil—or to his lieutenant, ʿAmr b. ʿUbayd (d. 144/761 [q.v.])—because on the question relating to the definition applicable …