Gurur Brahma Gurur Vishnuhu
Guru Devo Maheswaraha
Guru Saakshaat Parabhrahma
Tasmai Sri Gurave Namaha
गुरुर ब्रह्मा गुरुर विष्णु गुरु देवो महेश्वरः
गुरु साक्षात परब्रह्म तस्मै श्री गुरवे नमः
The true meaning of Guru is "one who dispels darkness of ignorance". "Gu" means "darkness of ignorance" and "Ru" means "one who removes". Guru resembles the trinity Brahma, Vishnu and Shiva. Brahma is creator. Guru creates or inculcates knowledge in the minds of the students. Guru is Vishnu. Lord Vishnu maintains the creation. Similarly Guru helps in keeping up the knowledge. Guru is like Shiva. Shiva is the destroyer. Guru destroys or gets rid of the ignorance from the students' minds.
Another meaning of the word Guru is "one who is beyond attributes and forms". Gu stands for Gunaatheetha - one who transcends the three Gunas (Satva, Rajas and Thamas); Ru stands for Rupavarjitha - one who is formless. The One who is beyond all attributes and forms is none other than the Supreme Self (the Brahmam) who is resident within each of us. Only God can be regarded as One who is beyond attributes and forms.