The period of continuation of stay of a Jīva (soul) in the same nikāya- form of life, in spite of undergoing the cycle of birth and death; e.g., a Jīva in the form of a human being may continue to reincarnate as the human being (for several births); the earth-bodied Jīva and the like may continue to remain in the same kind of Yoni (substratum suitable for the birth of the Jīva (soul)) for an innumerable period of time.
kāye- nikāye pṛthivyādisāmānyarupeṇa sthitiḥ kāyasthitiḥ asaṃkhyotsarppiṇyādikā.
(Sthā 2.159 Vṛ Pa 62)