In the Sanskrit language, guru means teacher. Eastern religions, such as Hinduism, Jainism, Buddhism, Sikhism and newer movements such as Transcendental Meditation use guru as a title. They give it to a teacher (or guide) of religious matters.

In Western usage, any person who has followers may be called a guru, even if he is followed for things other than religion or philosophy. A person with knowledge or expertise may be called a guru if he influences by personal teaching. Modern terms which have a rather similar meaning are mentor and tutor.