Ajaan (Thai): Teacher; mentor. Pāli form: Ācariya.

Arahant: A “worthy one” or “pure one;” a person whose mind is free of defilement and thus is not destined for further rebirth. A title for the Buddha and the highest level of his noble disciples. Sanskrit form: Arhat.

Bhikkhu: Monk.

Bhikkhunī: Nun.

Brahmā: A deva inhabiting the realms of form or formlessness.

Brahman: A member of the priestly caste, which claimed to be the highest caste in India, based on birth. In a specifically Buddhist usage, “brahman” can also mean an arahant, conveying the point that excellence is based not on birth or race, but on the qualities attained in the mind.

Deva: Literally, “shining one.” An inhabitant of the terrestrial and celestial realms higher than the human.

Dhamma: (1) Event; action; (2) a phenomenon in and of itself; (3) mental quality; (4) doctrine, teaching; (5) nibbāna (although there are passages describing nibbāna as the abandoning of all dhammas). When capitalized in this book, Dhamma means teaching. Sanskrit form: Dharma.

Gandhabba: A deva on one of the lower celestial levels, often portrayed as a trickster.

Jhāna: Mental absorption. A state of strong concentration, devoid of sensuality or unskillful thoughts, focused on a single physical sensation or mental notion which is then expanded to fill the whole range of one’s awareness. Jhāna is synonymous with right concentration, the eighth factor in the noble eightfold path. Sanskrit form: Dhyāna.

Kamma: Intentional act. Sanskrit form: Karma.

Māra: The personification of temptation and all forces, within and without, that create obstacles to release from saṁsāra.

Nibbāna: Literally, the “unbinding” of the mind from passion, aversion, and delusion, and from the entire round of death and rebirth. As this term also denotes the extinguishing of a fire, it carries connotations of stilling, cooling, and peace. “Total nibbāna” in some contexts denotes the experience of Awakening; in others, the final passing away of an arahant. Sanskrit form: Nirvāṇa.

Pāli: The language of the oldest extant complete Canon of the Buddha’s teachings.

Pāṭimokkha: The basic code of rules for monks and nuns. The monks’ code contains 227 rules; the nuns’, 311.

Saṁsāra: Transmigration; the process of wandering through repeated states of becoming, entailing repeated birth and death.

Saṁvega: A sense of overwhelming terror or dismay over the pointlessness of life as it is normally lived.

Saṅgha: On the conventional (sammati) level, this term denotes the communities of Buddhist monks and nuns. On the noble or ideal (ariya) level, it denotes those followers of the Buddha, lay or ordained, who have attained at least stream-entry.

Satipaṭṭhāna: Establishing of mindfulness; foundation of mindfulness. The meditative practice of focusing on a particular frame of reference—the body in and of itself, feelings in and of themselves, mind states in an of themselves, or mental qualities in an of themselves—ardent, alert, and mindfulness, putting aside greed and distress in reference to the world. This practice then forms the basis for jhāna.

Sutta: Discourse. Sanskrit form: Sūtra.

Tathāgata: Literally, “one who has become authentic (tatha-āgata),” or “one who is really gone (tatha-gata),” an epithet used in ancient India for a person who has attained the highest religious goal. In the Pali Canon, this usually denotes the Buddha, although occasionally it also denotes any of his arahant disciples.

Uposatha: Observance day, coinciding with the full moon, new moon, and half moons. Lay Buddhists often observe the eight precepts on this day. “Uposatha” also refers to the ceremony in which monks meet to listen to the recitation of the Pāṭimokkha on the full moon and new moon uposathas.

Vinaya: The monastic discipline, whose rules and traditions comprise six volumes in printed text.

Vipassanā: Insight. In the Pāli Canon, this denotes a quality of the mind. In modern Buddhism, it also denotes a type of meditation practice specifically aimed at developing insight.