Formal:
* குரு (Guru): The most common and direct translation. It is used in a respectful and formal context.
* ஆசான் (Aasan): This means "teacher" or "master" and is used to address a spiritual or intellectual guide with great respect.
Informal:
* கூர (KooRa): A more casual and informal way to address a guru, often used by those who are close to them.
Other terms:
* சத்குரு (Sadguru): This means "true guru" and is used to emphasize the authenticity and spiritual power of the guru.
* அருள்நெறி (Arulneri): This literally means "path of grace" and can be used to refer to a guru who is seen as a source of divine guidance.
The best way to address a guru in Tamil depends on the context and the relationship between you and the person.