Chi Qi Chi
Since the beginning of the year, as I've gotten back into Tai Chi at a level of intensity I haven't practiced at in a while, I started going to the local Tai Chi center. Most of the regulars and instructors are pretty focused on "chi". They also use the word "energy" as an alternate often, mostly so they don't just keep repeating the word chi over and over. I have the utmost respect for these people, though I also don't have an easy time with words used in a way that lacks concrete explanations.
Most of my training has been with one teacher who had two main Tai Chi teachers, both of whom talked in the language of body mechanics and physics. While "energy" may have been spoken of it was typically in the sense of where we put our attention, focus, or movement; there was no vague statements like "send your chi" or "use your chi". While people may sense an internal energy or "buzz" feeling they call chi, I'm not one of those people, so the overuse of the word chi often strikes me as either a way to claim more skill or experience, or a way to keep from having to describe what we're doing in plain language.
As is the case with many other practices out there, like yoga or meditation, many popular figures in the internal martial arts talk, at least occasionally, in vague language that imparts a mystical quality. This allows there to be a gate kept by the teacher that one can only pass through with the help of said teacher.
I heard someone recently try to explain that without being touched you can physically feel when someone is yelling at you. This was offered as an explanation of having energy bodies which extend out from our physical one, and I get and maybe even agree (to a degree) in the intent behind that idea, but if someone is yelling at me I am in fact physically being touched by the vibrations created by their yelling. It's not just some ethereal body of mine that is touching or being touched by them.
I understand the desire for something magical, in fact I think we all to a certain degree believe in "magic" of some sort. Things happen in ways that seem mystical but often the explanations are more concrete.
I recently picked up a book by one of my teacher's teachers, Dr. Tao Ping-Siang's Taiji Push Hands. Dr. Tao was not a large man but he had no problem moving anyone, or more accurately he never had a problem causing others to move themselves. At the beginning of chapter 1 (The Secret of Qi in Taiji Quan) he writes "In addition to these well known meanings for the word, there is one that is far less well known. It is the energy that exists in practicing Taiji Quan, and also in the movements of daily life, an energy that can be called 'momentum'. This is what I call 'quan qi', the Qi of Taiji Quan."