2004 Article by Dan Penrod

Movement in aikido is often categorized by 4 words; Irimi, Tenkan, Omote, and Ura. These 4 words can be used to help describe any attack combined with any defense. I hope to clarify the meaning and use of these words and describe the subtle relationship between these terms.

Before I begin, I should mention that I’ll be using the words nage and uke repeatedly. For the unitiated, nage means thrower and is generally the person who receives the attack and provides the throw, pin or neutralization. Uke means receiver and is usually the person who initiates the attack, but more specifically is the one who receives the throw.

Let’s begin with some basic definitions. You should pay attention to which words are verbs and which words are adverbs. This is the first clue to their relationships.

Irimi: verb. To enter. Refers to nage’s movement in relation to uke. Nage enters on a line toward uke as he receives an attack. Irimi is well represented by the symbol of the straight line.

Tenkan: verb. To turn. Refers to nage’s movement in relation to uke. Nage turns in a circular motion as he receives the attack, usually by pivoting on the front foot and describing a 90 to 180 degree semi-circle with the rear foot. Tenkan is well represented by the symbol of the circle.

Omote: adverb. In front of. Refers to the positional relationship of nage in regard to uke. Nage has moved in front of uke.
Ura: adverb. To the rear of. Refers to the positional relationship of nage in regard to uke. Nage has moved behind uke.
Ura is sometimes defined as the area outside or behind uke’s leading hand or foot while omote is viewed as the area inside or to the front of uke’s leading hand or foot. The most important thing to notice here is that as adverbs, omote and ura describe the verbs irimi and tenkan.

There is a 3rd verb we sometimes use which I’ll just briefly mention and leave at that because it falls somewhat outside the scope of this discussion.

Kaiten: adverb. Roughly translates as rotate. It’s applied when uke rotates 180 degrees… but unlike tenkan where the rear foot sweeps in a 180 degree semi-circle… the feet don’t move in kaiten. They pivot in place and the hips rotate to look in the opposite direction. Kaiten is, of course, used in kaiten nage, the rotating throw. It is also frequently used in conjunction with irimi to allow nage to reorient himself in the same direction as uke.

It’s important to notice that irimi and tenkan are diametrical opposites. Omote and ura are also opposites. Omote and ura share the x-axis while irimi and tenkan share the y-axis. Viewed as a compass, irimi is north, tenkan is south, omote is west, and ura is east. This compass model brings into focus not only the 4 compass directions, but more importantly the 4 quadrants movements between them; irimi omote, irimi ura, tenkan omote, and tenkan ura.

Irimi omote: Nage enters in front of uke.
Irimi ura: Nage enters to the rear of uke.
Tenkan omote: Nage turns to the front of uke.
Tenkan ura: Nage turns to the rear of uke.
These quadrants can be used to accurately describe the movement in an aikido technique. Let’s look at the syntactical structure used to describe an aikido movement.

syntax: <attack> <quadrant movement> <throw> <quadrant movement>
example:<yokomen uchi> <tenkan omote> <shiho nage> <tenkan ura>

The first quadrant movement describes how nage receives the attack. The second quadrant movement describes how nage throws uke. In our example here, nage receives the attack (side of head strike) with a tenkan omote or turning to the front of uke. Then nage throws with a shihonage (4 direction throw) using tenkan ura or turning to the rear of uke.

It is not uncommon for people to abbreviate terms by saying something like, yokomen uchi shihonage tenkan. While this description is accurate, it is not precise. There is more than one way to perform yokomen uchi shihonage tenkan. Specifically, there are 4 ways. Nage could receive the attack (yokomen uchi) with tenkan omote or tenkan ura. Also, nage could throw with a tenkan omote or tenkan ura movement (of shihonage).

Since there are 4 possibilities that can be applied in receiving the attack (first quadrant movement) and there are still 4 possibilities that can be applied in executing the throw (second quadrant movement) there could be a mind-numbing 2 ^4 = 16 possible combinations for just one technique. In practice there will be many fewer do to specifics characteristics of each technique. In the case of yokomen uchi shihonage, I submit there are 4 possibilites.

For other techniques the number of combinations will be different. How many for tsuki kotegaeshi? Or shomen uchi irimi nage. I’ll leave these calculations as an exercise for the reader.

Taking the time to fully recognize this model is more than an exercise in semantics. It opens the students mind to the possibilities and provides a tool for the student to discover techniques they may have never seen before.