Pali lit. "basket of the special (or higher) dhamma". The division of the Pali Canon (Tipitaka) of Buddhism that contains the Abhidhamma, the philisophical and metaphysical elaboration of the teachings found in the suttas of the Sutta Pitaka. The Abhidhamma Pitaka is unique in that it is formed not as a series of anecdotes relating to the Buddha and his students, but rather as a series of lists, treatises, and general theories. In this respect, it serves as a generalization of the principles taught to specific individuals at specific time in the many suttas of the Sutta Pitaka.
Additionally, the Abhidhamma Pitaka condences and cross-references the various ways in which different central concepts are referenced across the other books of the canon. In the course of delivering discourses to various groups and persons, the Buddha used various synonyms for concepts like the factors of enlightenment. It is not always clear that these differen words are referring to the same concepts, particularly since the texts use very technical and archaic forms of the long-dead Pali language. The Abhidhamma Pitaka aims to elucidate this problem, by grouping the various synonyms used by the Buddha together to illustrate the concept that they belong too.
The Abhidhamma also differs in textual style from the other divisions of the Pali Canon in that it does not make use of 'provisional' truths, such as the existence of individuals. While the Buddha, for clarity, taught to regular people in terms of concepts which, from a Buddhist perspective, have conventional but no ultimate existance, such as 'man', 'woman' 'person', 'you', 'me', the Abhidhamma speaks only in terms of those dhammas which are held to have existence outside of the conceptualizations of human beings. This makes the text much more dense and difficult from a reader's perspective, but less likely to lead one astray, from a philisophical perspective.