Dīgha Nikāya. The first book of the Sūtra Piṭaka of the Pāli Canon. It consists of 34 long (dīgha) discourses (suttas), divided into three sections known respectively as the Sīlakkhandha, the Mahāvagga, and the Pātheya or Pāṭikavagga. A number of the suttas, such as the Mahānidāna Sutta and Mahāsatipaṭṭhāna Sutta, expound important doctrines. Also, in many of the suttas, like the Soṇadaṇḍa Sutta and the Sāmaññaphala Sutta, the Buddha discusses the views and doctrines of Brahmanism and various contemporary religious schools and philosophies. The commentary on the Dīgha Nikāya, compiled in the 5th century by Buddhaghoṣa is known as the Sumaṇgalavilāsinī.

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