square (of a number); second power
Rare mathematical term for the square of a number; in modern Japanese, 二乗 (にじょう) or 2乗 is overwhelmingly more common.
See also: 二乗
In old mathematics books, the notation 二乗冪 can sometimes be seen.
Compound of 二乗 (にじょう, 'square') and 冪 (べき, 'power'). The kanji 冪 is rare in modern Japanese and is usually replaced by 乗 or mathematical notation.