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[edit] Atemi:　当身

(lit. Striking the Body) Strike directed at the attacker for purposes of unbalancing or distraction. Atemi is often vital for bypassing or "short-circuiting" an attacker's natural responses to aikido techniques. The first thing most people will do when they feel their body being manipulated in an unfamiliar way is to retract their limbs and drop their center of mass down and away from the person performing the technique. By judicious application of atemi, it is possible to create a "window of opportunity" in the attacker's natural defenses, facilitating the application of an aikido technique. Atemi can also be defined as a strike directed to a vital point and may be used to position the uke or set up the technique. Different styles, organizations, schools and instructors place varying emphasis on atemi. Some do not use atemi at all whereas others apply it judiciously. The failure to use atemi in a martial situation is viewed by some as a lack of understanding of the implications of an attack or violence.

AikiWeb Article: The Use of Atemi by George S. Ledyard