第二結集の後に上座部から分裂した初期仏教の部派の一つで、一部の経典を認めない点が特徴であり、後にさらにいくつかの支派を生み出した。

One of the early Buddhist schools that split from the Theravādins at the Second Council, distinguished by its rejection of certain canonical texts and later giving rise to several further sub-schools.