In Sanskrit, Guru means teacher and Yoga means union, but the word Guruyoga can also be translated as knowledge, understanding. In Tibetan, Yoga is translated as naljor: nal is the essential condition as is, in which there is nothing to change or to modify, and jor means to have or possess that knowledge. This is the state of the Guru. Therefore in the Dzogchen teaching being in the state of Guruyoga is the most important thing.
- Guru Yoga at RigpaWiki