Madhyama Āgama  (Sanskrit, middle collection). Sanskrit equivalent of the Pāli Majjhima Nikāya or ‘Middle-length Discourses’, being one of the main sections of the Sūtra Piṭaka (Pāli, Sutta Piṭaka). Many of the major Eighteen Schools of Early Buddhism had their own versions but for the most part these have not survived. As well as recent discoveries of small portions of the Sarvāstivāda Madyama Āgama in Sanskrit, and several sūtras from that tradition in Tibetan translation, a complete Sarvāstivādin version exists in Chinese. This contains 222 sūtras, in contrast to the 152 extant in Pāli.

A Dictionary of Buddhism, Oxford University Press, 2003, 2004 (which is available in electronic version from answer.com)