Nikāya

Nikāya is a Pāli word meaning "volume". It is often used like the Sanskrit word āgama to mean "collection", "assemblage", "class" or "group" in both Pāḷi and Sanskrit. It is most commonly used in reference to the Pali Buddhist texts of the Tripitaka namely those found in the Sutta Piṭaka. It is also used to refer to monastic lineages, where it is sometimes translated as a 'monastic fraternity'.
The term Nikāya Buddhism is sometimes used in contemporary scholarship to refer to the Buddhism of the early Buddhist schools.

Text collections

In the Pāli Canon, particularly, the "Discourse Basket" or Sutta Piṭaka, the meaning of nikāya 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 Piṭaka is broken up into five nikāyas:

the Dīgha Nikāya, the collection of long discourses
the Majjhima Nikāya, the collection of middle-length discourses
the Samyutta Nikāya, the collection of thematically linked discourses
the Anguttara Nikāya, the "gradual collection"
the Khuddaka Nikāya, the "minor collection"

In the other early Buddhist schools the alternate term āgama was used instead of nikāya to describe their Sutra Piṭakas. Thus the non-Mahāyāna portion of the Sanskrit-language Sutra Piṭaka is referred to as "the Āgamas" by Mahāyāna Buddhists. The Āgamas survive for the most part only in Classical Tibetan and Chinese translation. They correspond closely with the Pāḷi nikāyas.

Monastic divisions

Among the Theravāda nations of Southeast Asia and Sri Lanka, nikāya is also used as the term for a monastic division or lineage; these groupings are also sometimes called "monastic fraternities" or "frateries". Nikāyas may emerge among monastic groupings as a result of royal or government patronage, due to the national origin of their ordination lineage, because of differences in the interpretation of the monastic code, or due to other factors. These divisions do not rise to the level of forming separate sects within the Theravāda tradition, because they do not typically follow different doctrines or monastic codes, nor do these divisions extend to the laity.
In Myanmar, all the monastic orders are called gaing or gaṇa instead of nikāya, although some orders include Nikāya in addition to Gaing in their names. No new gaings have been allowed other than the nine legally recognized gaings under the 1990 Law Concerning Sangha Organizations. The largest of these is the Thudhamma Gaing, which was founded in the 1800s during the Konbaung dynasty.

Nikaya Buddhism

The term Nikāya Buddhism was coined by Masatoshi Nagatomifake as a non-derogatory substitute for Hinayana, meaning the early Buddhist schools. Examples of these groups are pre-sectarian Buddhism and the early Buddhist schools. Some scholars exclude pre-sectarian Buddhism when using the term. The term Theravada refers to Buddhist practices based on these early teachings, as preserved in the Pāli Canon.