noun
circular error probable; CEP
Technical term used in ballistics and missile accuracy measurement. Refers to the radius of a circle within which half of the projectiles are expected to land.
このミサイルの半数必中界は約50メートルと推定されている。
The CEP of this missile is estimated to be about 50 meters.
Compound of 半数 (half the number), 必中 (certain hit), and 界 (boundary/range). The term is a Japanese calque or translation of the English 'circular error probable'.