From B.K.S. Iyengar's Light on the Yoga Sutras of Patanjali:
Yoga is the cessation of movements in the consciousness.
1.2 - yogah cittavritti nirodhah
- union or integration from the outermost layer to the innermost self, that is, from the skin to the muscles, bones, nerves, mind, intellect, will, consciousness and self
- consciousness, which is made up of three factors: mind (manas), intellect (buddhi) and ego (ahamkara). Citta is the vehicle of observation, attention, aims and reason; it has three functions, cognition, conation or volition, and motion
- state of mind, fluctuations in mind, course of conduct, behavior, a state of being, mode of action, movement, function, operation
- obstruction, stoppage, opposition, annihilation, restraint, control, cessation