Sanskrit, if you ever have a chance to learn it, is quite an interesting language. Often, one word has many meanings. I suppose this is why the translations of yogic texts vary greatly. It makes studying the Yoga Sutras feel like cracking some sort of ancient code.
It reminds me how definitions can heavily influence what they are applied to. How you define your yoga practice, how you define yourself, how you define your life -- the answers to these questions can be the difference between bliss and injury, ease and doubt, happiness and suffering.
Yoga has many definitions. And, of course, outside of the formal or classical definitions of yoga are the practitioner's definition of yoga. For one person, a yoga practice may be defined as relaxation whereas to another it may be defined as strength-building. Granted, there are often basic standards in defining what yoga is.