The term yoga is used in so many contexts and in so many ways, it’s hard these days to know what anyone is talking about when they say something like “I do yoga” or “I study yoga” or “I teach yoga.” Thanks to this great book on yoga dedicated to an emeritus professor here at IU, I think I now have a little bit more of a grasp on what yoga means.
Yoga has five principle meanings, according to the editor of this book, Theory and Practice of Yoga: Essays Dedicated to Gerald James Larson. These are, in no particular order:
1) a system of discipline for the attainment of some goal;
2) the goal of this system of discipline;
3) the name of one of the six primary schools of Hindu philosophy (darsana);
4) a word combined with terms like hatha-, mantra-, tantra-, astanga-, etc. to refer to a specific tradition which specializes in a particular yoga technique or philosophy
5) the techniques of controlling the body and/or the mind.
A sixth use/meaning of the term yoga, and probably the one most common in the U.S., is simply to refer to a kind of fitness and health exercises (asana), which may or may not also include breathing techniques (pranayama) and/or meditation (dhyana).
Importantly, yoga did not mean “yoke” or “union” in its classical usage, despite what most yoga teachers and popular writers on yoga say today. But, as many contemporary scholars of Indian philosophy will point out, it would indeed be odd for yoga to mean something like “yoke” or “union” since the objective of Patanjali’s yoga, as it is laid out in the Yoga-Sutra, is for the yogi to recognize and realize the true nature of the universe – i.e. that pure consciousness (purusa) is distinct from mere matter (prakrti), which includes our minds and our thoughts. In other words, the yogi does not seek union or oneness with the world; rather, he seeks to liberate himself from his attachment to the worldly.
There are, of course, many other distinctions to make with respect to the term yoga, but I’ll set those aside for now so as not to confuse my main point here, which is as follows. When someone says “yoga” in a contemporary context, it is important to clarify what that person is trying to say. We ought not to assume what the person means, and, as we will often find, if we ask the person for some further clarification, we may be surprised to find out that he/she has a very different understanding of what yoga is than we do.