Gurumurthi is one of the forms of Lord Shiva. In the form of Gurumurthi, Lord Shiva is considered as Teacher, who teaches about the divinity and spirituality. Lord Shiva is being worshipped as Gurumurthi on Thursdays in many Shaivite temples, as Thursday is considered as the day of Gurus.
It is found in several epics that Lord Shiva has been considered as Guru and originated a Practice in Shaivism. One of such Practices where Lord Shiva is treated as the Teacher can be found in Pashupata Shaivism. The teachings of Pashupata Shaivism are said to be originated by Lord Shiva himself, after being reincarnated to a teacher called Likulisa, who in turn considered as Founder of Pashupata Shaivism.
According to the Legend, Lord Shiva unfolds his intention saying that he would once appear on the earth during the reign of Lord Krishna and designates that he would enter a dead body. Following his word, Lord Shiva reincarnates as Likulisa.
As Gurumurthi, Lord Shiva explains to all the Beings about the reason of the birth and the how Karma is associated with every Living Being in this Universe. He also teaches how to attain the stage of liberation, which is called Moksha or Mukti, by the means of Yoga and Meditation.
By practicing Yoga and Meditation, one can develop the concept of attaining the cosmic energy which leads to the stage where one can feel the Power and Grace of Lord Shiva. As Gurumurthi, Lord Shiva gives the opportunity to his devotees to get well associated with the life filled with Spirituality.