Yoga is means union. Traditional text explains this as a union of self with the universal self (energy). When duality cease to exist and we become one with the universe itself. This needs continued practice (only only the asanas but more so wrt the mental and attitude of ourselves). But in today’s context Yoga has been reduced to Yoga Asana (one the aspects) or the physical posture. And that too about the anatomical structure of the asana.