Nik?ya is a P?li word meaning "volume". It is often used like the Sanskrit word ?gama to mean "collection", "assemblage", "class" or "group" in both Pi and Sanskrit. It is most commonly used in reference to the Buddhist texts of the Sutta Pi?aka but can also refer to the monastic divisions of Therav?da Buddhism.
In addition, the term Nik?ya is sometimes used in contemporary scholarship to refer to early Buddhist schools.
In the P?li Canon, particularly, the "Discourse Basket" or Sutta Pi?aka, the meaning of nik?ya is roughly equivalent to the English collection and is used to describe groupings of discourses according to theme, length, or other categories. For example, the Sutta Pi?aka is broken up into five nik?yas:
In the other early Buddhist schools the alternate term ?gama was used instead of nik?ya to describe their Sutra Pi?akas. Thus the non-Mah?y?na portion of the Sanskrit-language Sutra Pi?aka is referred to as "the ?gamas" by Mah?y?na Buddhists. The ?gamas survive for the most part only in Classical Tibetan and Chinese translation. They correspond closely with the Pi nik?yas.
Among the Therav?da nations of Southeast Asia and Sri Lanka, nik?ya is also used as the term for a monastic division or lineage; these groupings are also sometimes called "monastic fraternities" or "frateries". Nik?yas may emerge among monastic groupings as a result of royal or government patronage (such as the Dhammayuttika Nik?ya of Thailand, due to the national origin of their ordination lineage (the Siam Nik?ya of Sri Lanka), because of differences in the interpretation of the monastic code, or due to other factors (such as the Amarapura Nik?ya in Sri Lanka, which emerged as a reaction to caste restrictions within the Siam Nik?ya). These divisions do not rise to the level of forming separate sects within the Therav?da tradition, because they do not typically follow different doctrines or monastic codes, nor do these divisions extend to the laity.
In Burma, nikaya monastic orders have emerged in response to the relative conservativeness with which the Vinayas are interpreted, and the hierarchical structure within the nikaya. Since 1980, no new nikayas have been allowed, and there are a total of nine legally recognized monastic orders in Burma today under the 1990 Law Concerning Sangha Organizations. The largest of these is the Thudhamma Nikaya, which was founded in the 1800s during the Konbaung Dynasty.