thumb|The guru-smiti relationship. Watercolour, Punjab Hills, India, 1740.
Guru ( ; IAST: guru) is a Sanskrit term for a "mentor, guide, expert, or master" of certain knowledge or field. In pan-Indian traditions, a guru is more than a teacher: traditionally, the guru is a reverential figure to the disciple (or shisya in Sanskrit, literally seeker [of knowledge or truth]) or student, with the guru serving as a "counsellor, who helps mould values, shares experiential knowledge as much as literal knowledge, an exemplar in life, an inspirational source and who helps in the spiritual evolution of a student".
The oldest references to the concept of guru are found in the earliest Vedic texts of Hinduism. Beyond a teacher of specific knowledge, "guru" in Sanskrit refers to someone who dispels darkness. Here, darkness denotes the ignorance in the person, due to lack of higher knowledge and because of which the person is continuously rotating in cycle of birth-death instead of getting liberated.
Guru is also a "counselor, a sort of parent of mind (Citta) and Self (Atman), who helps mold values (Yamas and Niyamas) and experiential knowledge as much as specific knowledge, an exemplar in life, an inspirational source and who reveals the meaning of life."|group=Note heavy with spiritual wisdom, "heavy with spiritual weight," "heavy with the good qualities of scriptures and realization," or "heavy with a wealth of knowledge." The word has its roots in the Sanskrit gri (to invoke, or to praise), and may have a connection to the word gur, meaning 'to raise, lift up, or to make an effort'.
Sanskrit guru is cognate with Latin gravis 'heavy; grave, weighty, serious' and Greek βαρύς barus 'heavy'. All three derive from the Proto-Indo-European root *gʷerə-, specifically from the zero-grade form *gʷr̥ə-.
Darkness and light
A popular etymological theory considers the term "guru" to be based on the syllables gu () and ru (), which it claims stands for darkness and "light that dispels it", respectively. The guru is seen as the one who "dispels the darkness of ignorance."