See also Subitizing

The term Subitism points to sudden enlightenment in Buddhism, the idea that insight into the True Nature or emptiness of the self is all at once.

The application of the term to Buddhism is derived from the French illumination subite (sudden awakening), contrasting with 'illumination graduelle' (gradual awakening). It gained currency in this use in English from the work of sinologist Paul Demiéville. His 1947 work 'Mirror of the Mind' was widely read in the U.S. It inaugurated a series by him on subitism and gradualism.

The term is used in Ch'an and Zen discourse to denote the doctrinal position that awakening or enlightenment (kensho, bodhi or satori) is instantaneous, sudden and direct, not attained by practice through a period of time, and not the fruit of a gradual accretion or realisation. Aspects of Dzogchen and Mahamudra may be referred to as subitist, as well as the Rinzai school.

In the Fivefold Classification of the Huayan school and the Five Periods and Eight Teachings of the Tiantai-school the sudden teaching was given a high place, but still inferior to the Complete or Perfect teachings of these schools.