Yoga:

This terse definition hinges on the meaning of three Sanskrit terms. I. K. Taimni translates it as "Yoga is the inhibition (nirodhaḥ) of the modifications (vṛtti) of the mind (citta)".[32] The use of the word nirodhaḥ in the opening definition of yoga is an example of the important role that Buddhist technical terminology and concepts play in the Yoga Sutra; this role suggests that Patanjali was aware of Buddhist ideas and wove them into his system.[33] Swami Vivekananda translates the sutra as "Yoga is restraining the mind-stuff (Citta) from taking various forms (Vrittis)."[34]
A sculpture of a Hindu yogi in the Birla Mandir, Delhi
Patanjali's writing also became the basis for a system referred to as "Ashtanga Yoga" ("Eight-Limbed Yoga"). This eight-limbed concept derived from the 29th Sutra of the 2nd book, and is a core characteristic of practically every Raja yoga variation taught today. The Eight Limbs are:
(1) Yama (The five "abstentions"): non-violence, non-lying, non-covetousness, non-sensuality, and non-possessiveness.
(2) Niyama (The five "observances"): purity, contentment, austerity, study, and surrender to god.
(3) Asana: Literally means "seat", and in Patanjali's Sutras refers to the seated position used for meditation.
(4) Pranayama ("Lengthening Prāna"): Prāna, life force, or vital energy, particularly, the breath, "āyāma", to lengthen or extend. Also interpreted as control of the life force.
(5) Pratyahara ("Abstraction"): Withdrawal of the sense organs from external objects.
(6) Dharana ("Concentration"): Fixing the attention on a single object.
(7) Dhyana ("Meditation"): Intense contemplation of the nature of the object of meditation.
(8) Samādhi ("Liberation"): merging consciousness with the object of meditation