The time during which a world is created and destroyed.

A complete cosmogonic cycle that includes four intermediate eons: the eon of formation (vivartakalpa; chags pa’si bskal pa), the eon of stability (vivartasthāyi­kalpa; gnas pa’i bskal pa), the eon of dissolution (saṃvartakalpa; ’jig pa’i bskal pa), and the eon of nothingness (saṃvartasthāyi­kalpa; stong pa’i bskal pa).

Definitions regarding the duration of one “great eon” vary, but are normally given in billions of (human) years. One great eon is divided into eighty intermediate eons, or, according to a different system, into four. Both systems of division are reconciled by grouping the eighty intermediate eons into four units of twenty.

The name of a certain kind of kalpa. The number of years in this kalpa differs in the various sūtras that give it a number, although it is said to equal four asaṃkhyeya (“incalculable”) kalpas.