Squared

A number taken to the power 2 is said to be squared, so  is called " squared." This terminology derives from the fact that the area of a square of edge length  is given by , hence the operation taking a square's edge length to its area is known as "squaring" and the quantity  derived from  by squaring is known as " squared."

Not that the term "squaring" also refers to the geometric construction, using only compass and straightedge, of a square which has the same area as a given geometric figure.