noun
strike to a vital point; atemi (martial arts)
In martial arts such as judo, aikido, and karate, 当て身 refers to a strike aimed at a vulnerable area of the body. The term is often used in technical discussions of striking techniques.
柔道では当て身は試合で禁止されている。
In judo, atemi (strikes to vital points) are prohibited in competition.
合気道の当て身は相手のバランスを崩すために使われる。
In aikido, atemi are used to break the opponent's balance.
急所 refers to a vital point on the body in general, while 当て身 specifically denotes a strike aimed at such a point in martial arts.
Compound of 当て (ate, 'striking' or 'hitting') and 身 (mi, 'body'). The term is native to Japanese martial arts vocabulary.