Satguru

In some eastern religions, a Satguru (or Sadguru) is a person who is considered to have achieved enlightenment, and who can help others to achieve the same. The word means "true teacher" in Sanskrit (), "sat" meaning "true" and a guru meaning "teacher". The title means that his students have faith that the guru can be trusted and will lead them to moksha, nirvana or inner peace. It is based on a long line of Hindu understandings about the importance of the guru.
Ancient and traditional sources.
In the "Guru Gita", Shiva says to Parvati:
The Kularnava Tantra (XIV/65) states,
"It is very rare to find a Satguru who can give "Shaktipat" and rare to find a disciple worthy of receiving it. One gets such a Guru only as a result of past meritorious actions."
In the Upanishads, five signs of satguru (true guru) are mentioned.
In the presence of the satguru; Knowledge flourishes ("Gyana raksha"); Sorrow diminishes ("Dukha kshaya"); Joy wells up without any reason ("Sukha aavirbhava"); Abundance dawns ("Samriddhi"); All talents manifest ("Sarva samvardhan").
According to Satguru Sivaya Subramuniyaswami, a Hindu Satguru is always a "sannyasin", an unmarried renunciate.