expression, noun
one-half; 50%
Used as a noun or expression to indicate the fraction 1/2 or a fifty-percent share.
ケーキを二分の一に切ってください。
Please cut the cake in half.
参加者の二分の一が女性だった。
Half of the participants were women.
Compound of 二 (two), 分 (part), の (possessive particle), and 一 (one), literally 'one of two parts'.