Square

In geometry, a square is a regularquadrilateral, which means that it has four equal sides and four equal angles (90-degree angles, or 100-gradian angles or right angles). It can also be defined as a rectangle in which two adjacent sides have equal length. A square with verticesABCD would be denoted {\displaystyle \square }ABCD.^[1][2]

source: https://en.wikipedia.org/wiki/Square