also: かくがっこ
noun
Refers to the punctuation marks [ and ]. Used in writing, programming, and mathematics.
角括弧で囲まれた部分は省略可能です。
The part enclosed in square brackets can be omitted.
プログラミングでは、配列のインデックスに角括弧を
In programming, square brackets are used for array indices.
Compound of 角 (kaku, 'angle') and 括弧 (kakko, 'brackets'), referring to the angular shape of square brackets.