Ajari (also Azari, Sanskrit: acarya, also transliterated as Ajariya) means a "model/example" in Sanskrit, and is a master who is an example to his disciples and teaches the dharma.
In the vedic religion, this term referred to a leader who instructed his followers using examples from the vedas, while in Nikaya Buddhism, it referred to a high-ranking monk who led monks in training and instructed them in doctrine; so while the exact meaning varied according to the particular religion, the term Ajari was used in several instances in the sense of leadership.
In esoteric Buddhism, it sometimes refers to Vairocana and the other Buddhas, but in general it is a title for priests in a high position who should be an example for the other monks; in Japan in the Tendai and Shingon sects, it is a position given to noble monks, especially to those who conduct rites in ceremonies involving the emperor.
Among the monks called Ajari in Japan are:
Kyoju Ajari – Teaches the Dharma;
Demp Ajari - Those who have received a kanjo (a ceremony to be the successor) of the denpo (all of the necessary elements for preservation and development of the techniques and sutras).
Shichikozan Ajari – Especially at Enryaku-ji Temple, Mt. Ibuki, and Atago-jinja Shrine (Kyoto City), one who has received a designation from the imperial court and has been given an imperial command to pray in a temple that conducts ceremonies to pray for abundant harvest, and works as an officiating monk;
Isshin Ajari – Members of the imperial family or Sekkan-ke (the families which produced regents) who entered the priesthood while young and were allowed the title of Ajari at a young age by virtue of their noble birth became this;
et cetera. Also, a Denpo Ajari of especially great virtue was called a Great Ajari.