In Euclidean plane geometry, a **rectangle** is any quadrilateral with four right angles. Another name is **equiangular quadrilateral**, since equiangular means that all of its angles are equal (360°/4 = 90°). It can also be defined as a parallelogram containing a right angle. The term **oblong** is occasionally used to refer to a non-square rectangle. A rectangle with vertices *ABCD* would be denoted as *ABCD*.

The word rectangle comes from the Latin *rectangulus*, which is a combination of *rectus* (right) and *angulus* (angle).

A so-called **crossed rectangle** is a crossed (self-intersecting) quadrilateral which consists of two opposite sides of a rectangle along with the two diagonals. It is a special case of an antiparallelogram, and its angles are not right angles. Other geometries, such as spherical, elliptic, and hyperbolic, have so-called rectangles with opposite sides equal in length and equal angles that are not right angles.

Rectangles are involved in many tiling problems, such as tiling the plane by rectangles or tiling a rectangle by polygons.

Read more about Rectangle: Characterizations, Formulas, Theorems, Crossed Rectangles, Other Rectangles, Tessellations, Squared, Perfect, and Other Tiled Rectangles