Aiki (Ã¥ÂÂæ°Â, "joining spirit"), a Japanese budà  term, at its most basic is a principle that allows a conditioned practitioner to negate or redirect an opponent's power. When applied, the practitioner controls the actions of the attacker with minimal effort and with a distinct absence of muscular tension usually associated with physical effort.
In Japanese Aiki is formed from two kanji:
The kanji for is made of three radicals, "join", "one" and "mouth". Hence, symbolizes things coming together, merging. should not be confused with which refers to harmony. The kanji for represents a pot filled with steaming rice and a lid on it. Hence, symbolizes energy (in the body).
Thus 's meaning is to fit, join, or combine energy. However, care must be taken about the absolute meanings of words when discussing concepts derived from other cultures and expressed in different languages. This is particularly true when the words we use today have been derived from symbols, in this case, Japanese kanji, which represent ideas rather than literal translations of the components. Historical use of a term can influence meanings and be passed down by those wishing to illustrate ideas with the best word or phrase available to them. In this way, there may be a divergence of the meaning between arts or schools within the same art. The characters and have translations to many different English words.
Historically, the principle of would be primarily transmitted orally, as such teachings were often a closely guarded secret. In modern times, the description of the concept varies from the physical to vague and open-ended, or more concerned with spiritual aspects.
lends its name to various Japanese martial arts, most notably Aikido, and its parent art, Daito-ryu aiki-jujutsu. These arts tend to use the principle of as a core element underpinning the bulk of their techniques. is an important principle in several other arts such as Kito-ryu, Judo, Yamabujin Goshin jutsu and various forms of Kenjutsu and Japanese Jujutsu. Techniques accomplished with are subtle and require little mechanical force with the arts generally classed as soft internal martial arts.
is a complex concept, and three aspects have been used to describe it in relation to a martial situation:
1) Blending, not clashing
2) Leading the assailant
3) Use of internal strength â Ki energy
is considered to be an ancient practice, and its practice is often kept within a particular individual or two from a family/school lineage. Culturally, and due to certain necessities of the time period, the knowledge was usually a very well-guarded secret and rarely disclosed.
The oldest book to have historically discussed was the 1899 Budo Hiketsu-Aiki no Jutsu. On the subject of it was written:
The Textbook of Jujutsu (Jujutsu Kyoju-sho Ryu no Maki) from 1913 stated:
The term has been used since ancient times and is not unique to . The in is , meaning to respond to an attack.