Pratyekabuddhayāna (Sanskrit; traditional Chinese: 緣覺乘; pinyin: Yuánjué Shèng) is a Buddhist term that refers to the path,
or vehicle, of a pratyekabuddha ("solitary awakened one").
This term was used in Indian Buddhism by early Buddhist schools, and is also used by the Mahāyāna tradition.
At least some of the early Buddhist schools used the concept of three vehicles including Pratyekabuddhayāna.
For example, the Vaibhāṣika Sarvāstivādins are known to have employed the outlook of Buddhist practice as consisting of the Three Vehicles:
concept of three vehicles
The Dharmaguptakas regarded the path of a pratyekabuddha (pratyekabuddhayāna) and the path of a bodhisattva (bodhisattvayāna) to be separate.
One of their tenets reads, "The Buddha and those of the Two Vehicles, although they have one and the same liberation, have followed different noble paths."
In the 4th century Mahāyāna abhidharma work Abhidharmasamuccaya, Asaṅga describes those who follow the Śrāvaka Vehicle (Skt. śrāvakayanika).
These people are described as having weak faculties, following the Śrāvaka Dharma, utilizing the Śrāvaka Piṭaka, being set on their own liberation, and cultivating detachment in order to attain liberation.
While those in the Pratyekabuddha Vehicle (Skt. pratyekabuddhayānika) are portrayed as also utilizing the Śrāvaka Piṭaka, they are said to have medium faculties, to follow the Pratyekabuddha Dharma, and to be set on their own personal enlightenment.
Finally, those in the Mahāyāna (Skt. mahāyānika) are portrayed as utilizing the Bodhisattva Piṭaka, as having sharp faculties, following the Bodhisattva Dharma, and set on the perfection and liberation of all beings, and the attainment of complete enlightenment.