Hi David, Steve, Louis and everyone else,
Dave, thanks for the vote of confidence about the glossary, but I fear I lack the qualifications and time to attempt anything comprehensive. If you have a particular list of words in mind, however, I might be able to give it a shot for others to pick apart.
Steve and Dave, as for the terminology describing the various jins, I can add the following. The term "jin" itself gives no linguistic clues as to the T'ai Chi uses of this term, other than a connotation of integration, as dicussed earlier on other threads. The short tag I would give the term would be "integrated strength or power."
As for peng, lu (with two dots on the "u"), ji, an, cai, lie, zhou, and kao, all of these characters can apparently be written with a picture of a hand on the left side (the hand radical) that looks like a "t", except with the bottom hooking toward the left and an extra crossing stroke near the bottom of the stem that slants upward from left to right. In my meager reading of T'ai Chi in Chinese, I have seen the hand radical used in the characters for "zhou" and "kao" only in Yang Zhen Duo's book when he quotes from his father's book. The significance of the presence of this radical is that all the characters would be seen as basically indicating hand manipulations or techniques. This should not be taken too literally, however, because there are many instances in Chinese where characters have taken on or always had expanded or figurative meanings that go beyond what the composition of the character would indicate.
Here are my operating definitions based on linguistic grounds. "Peng" would be to "manipulate something to provide shelter for something." "Lu" is problematic, but my best guess would be that it "means" to "manipulate with constant pressure, as if trodding slowly on something or stroking it." "Ji" would be to "squeeze either the hands or different energies together." "An" would be to "press onto something." "Cai" would be to "pluck" something. "Zhou" would be to "manipulate with the shoulder." "Kao" would be to "bump up against something."
"Lie" is somewhat problematic. I posed a brief question to Yang Jwing Ming about this character at his stall during one of the Zhang San Feng Festivals at the T'ai Chi Farm. He said that the character was unique to T'ai Chi. I can confirm that there are three graphically related characters with the same pronunciation, and I have been unable to find the T'ai Chi one in any dictionaries.
Homophones are extremely common in Chinese and graphical similarity only occasionally indicates that the spoken words are etymologically related. Sometimes, in fact, related spoken words (in classical and modern Chinese) have been expressed by graphically unrelated characters.
Of the three characters I refer to above, the basic one is a picture of a vertebra on the left and a knife blade on the right and is thought to convey an idea of "cut up or butcher a piece of meat in the proper sequence (vertebra by vertebra?)." The basic meaning, however, is to arrange in order or in a row.
The T'ai Chi character adds the hand radical to the left of this, which would indicate a meaning something like "manipulate something into order or in a row." This putative meaning seems prettly unhelpful for T'ai Chi practice, however.
The third character adds a picture of a gown (the clothing radical) under the vertebra and the knife blade and means to split or tear (open or in two) and can refer to fruits, seeds, skin, vessels, clothing, etc. As far as I know, it does not refer to "tearing off," but I defer to Jerry, Louis, or other real Chinese speakers on this point. Given that the oral tradition has given "split" as the meaning of the T'ai Chi character, I believe that the third character, rather than the first one (to arrange in order), is the one that gives the T'ai Chi character its meaning.
I personally gloss T'ai Chi "lie" as meaning "to bisect lines of energy (force vectors) or to use energy in opposing directions to set up a rotation." An example of the first would be to use roll back ("lu") and pluck ("cai") with one arm to extend the opponent's arm and then to use your other forearm to break your opponent's elbow. An example of the second would be "Parting Wild Horses Mane," where you can step to the side and rear of your opponent with one leg and use your lower arm to topple the opponent over your thigh.
I have read many descriptions of the four square or straight (zheng1) energies (peng, lu, ji, and an) that relate them primarily to directions: up, back (or sideways), forward, and down, respectively. I personally do not find any real support for this linguistically, although I do not see any inherent obstacles to such interpretations. I do not like them because I see nothing uniquely evocative of T'ai Chi techniques or strategy to such descriptions.
As I reconsider this position while writing this, perhaps it is best to think of these energies has having four typical components: a situation, a hand and arm shape, a mental focus (jin point?), and a direction.
Starting from the push hands routines, which were designed to practice the four square energies, one could view the energies this way. The situation for using generalized peng energy would be keeping the opponent away from one's center, by aborbing his or her energy and returning it to him or her. The characteristic shape would be keeping one's arm in an arc to provide maximum protection, with the hand higher than the elbow and the pinky side of the palm rotated slightly inward and upward to best connect the arm to the body. The focus of the mind would be the outer surface of the forearm from elbow to wrist, and the direction would be outward from one's center.
Specific peng energy would differ from the generalized peng energy as follows. The situation would be receiving an attack above one's arms and diverting the opponent's energy upward off its most powerful trajectory and circling it back into the opponent. The shape would be the same. The mental focus would change to the thumb edge of the forearm near the wrist. And the characteristic direction would change to upward.
In "lu" (roll back), the situation would be diverting the opponent's mid-level attacking energy to the side and to the rear. The shape would start the same as in "peng," but would change by rotating the palm upward and dropping the elbow slightly. Also the other forearm comes into play to assist, as one's side becomes exposed. The mental focus is on the back of the forearm, wrist, and hand of the primary arm and on the pinky edge and inner side of the assisting arm. The direction is sideways and rearward.
In "ji," the situation would be dealing with having one's side exposed and diverting the attacking energy forward into the opponent. The shape would be using one arm and hand to increase the ward off energy and shape in the other hand. The focus would be on the outside of the ward off arm and wrist and on the palm heel of the assisting hand. The typical direction would be forward.
In "an," the situation would be needing to confront an attack below the arms or from the outside, as in an attempted two-hand choke. The shape would be using the seated elbows and wrists of both hands independently, but linked through the mid back. The focus would be on the fingers, palms, and palm heels. The direction would be downward.
All of these techniques seem geared to solving recurring problems in push hands or close-in fighting or clinching. The four elements would be varied, depending on the specific application, the position and intention of the opponent, etc. With this interpretation, no one element would define these energies, but rather the combination of all of them in their infinite variation.
The four diagonal (or corner)(yu4) energies, cai (pluck), lie (split), zhou (elbow), and kao (shoulder stroke or bump), would be supplemental techniques that round out the square (or straight) energies. "Cai" would add grasping to extend the opponents energy out of his or her root. "Lie" would add intersection of energy vectors to split joints or set up body rotations. "Zhou" (literally, "elbow") would add use of the elbow, and "kao" (literally, "be next to", "lean on," "oppose") would add use of the torso through the shoulder, back, or hip.
As I understand it, all the eight primary energies are present in each of the form postures to varying degrees and, as such, should not be thought of as completely separate. An attempt to apply this logic to a posture such as roll back would be as follows.
You are standing with arms at the side and your opponent attempts to shove you with both hands or punch to your mid section with the left hand. You then use "peng" energy in your left arm by circling the left arm vertically counterclockwise to lift the opponent's arm off target with the thumb side of the wrist and forearm while aborbing some of the energy. You then use "lu" by stepping back with the left leg to further yield and absorb, turn the waist to the left and return some of the energy to the side as you stick to the attacking wrist with the outside of your left arm. As your side becomes exposed you use your right forearm to stick to the opponent's elbow. You then use "cai" by snaking your left arm counterclockwise around the opponent's arm and grasping and twisting it lightly by the wrist to extend the opponent's arm and energy to the rear and side. You use "ji" to squeeze your hands slightly towards each other and lock the opponent's elbow joint. You use "an" by pressing the opponent's forearm downward with your forearm and further drawing him or her out of his or her root. You use "lie" by drawing the opponent's energy out with the left arm and splitting through the elbow joint either to dislocate it or to use leverage to bounce the opponent out. You use "zhou" by reposition your right elbow to adjust or perform the right forearm techniques. "Kao" is inherent in rotating the whole body counterclockwise to add force to the right arm techniques or to perform them directly if the right arm gets out of position.
In addition to the eight primary energies, there would, of course, be other energies or qualities used in this one application, such as listening, understanding, adhering, sticking, transforming, seizing, issuing, filing, short snapping, long drawing out, suddeness, etc.
Steve, you referred to the corner energies as "short." Can you elaborate on this point? I believe I have heard descriptions of "zhou" as "short and fierce," and I believe I recall Horacio as quoting Yang Zhen Duo as referring to "lie" as being like a dragon fly skipping off the surface of water. I do not recall anything similar that is said about "kao" or "cai." In fact, I have always thought of "kao" as requiring "long energy" because of the particular need to bring energy up from the feet. Do you (or does anyone else) have a useful definition of "short" energy?
Louis, I like your comment about these definitions setting forth subjective mapping of the experiences, rather than describing objective phenomena. I have forgotten this too often to my detriment.
Recently, I was at a seminar of a T'ai Chi master in New Jersey. He was having the students explore an application of the Beginning (or Arising) Posture of his style in which the opponent is grabbing both of your wrists, which are hanging down by your sides. You then raise both arms diagonally forward and upward in arcs, like two parentheses, while circling and twisting the wrists with the thumb sides inward, downward, then outward (i.e., leading with the pinky side). This uproots and forces the opponent to his or her rear.
I was having trouble performing this applicating and tried all sorts of variant angles of arcs and twists. I was advised by my partner to sink more, but I avoided following this advice, because I knew that even if I sank by tailbone to the floor, it would not change my lack of feeling. Also, I am fairly strong and knew that I could use brute strength and changes in my body positioning to move my partner without gaining any T'ai Chi insight.
The teacher saw my difficulty. Rather than giving me any physical advice, he told me that my mental focus was too internal and not sufficiently on my opponent. Also, he mentioned that all I should be trying to do is use my open back to close my opponent's back. With this advice, I immediately understood what was wrong, moved my arms only a few inches to uproot my partner and could feel a difference of night and day. The teacher looked me in the eye and said: "Now you've got it."
Although I needed a physical approach to learn the technique, a purely physical approach would never have been sufficient for me. Also, such an approach could never sufficiently take into account variations in arm length, the strength of the opponents grip, the strength exerted by their wrists, elbows, and shoulders, the degree of tension in their mid back, etc.