Several definition of ‘yoga’ exist wherein attempts have been made to convey a comprehensive understanding of yogabut actually none of the definition compass all the aspects of yoga. The most systematic literature on yoga is  Patanjala Yoga Darshan. Maharshi Patanjali defines yoga as:

(P.Y.D. I/2)

i.e. yoga is a state of nirodha (cessation) of all the vrittis (functuations) in chitta (the mental being or the inner instrument of cognition and consciousness).

Any intelligent person identifes himself with the changing modes of chitta consciousness like pramana viparyaya vikalpa nidra smriti. Those layers of changing modes cover the self and patanjali provides techniques to uncover them through his analysis.

Various definitions of yoga in Bhagwad Gita are as:

(Bhagwad Gita 2/48)

i.e. ‘Evenness (of mind) is Yoga.’

Here action with an attitude of detachment to fruit of action is yoga.

(Bhagwad Gita2/50)

i.e. ‘Yoga is Skillfulness in Action.’

Here skill in action works as means for the attainment of yoga i.e. ‘samadhi’