Plane geometric figure with four congruent sides and four right angles.
The term is also used to refer to a measure of area such as the
square metre.
Historical note
Originally, the term "square" referred to the geometric figure we still call a square. Greek mathematicians later used the term "square" to refer to the more abstract concept of a number [latex]c^{2}[/latex] which represents the area of a square with side length c units.
