A quadrilateral, in geometry, is a polygon with 4 sides.
Quadrilateral may also refer to:
- Complete quadrilateral, in projective geometry, a configuration with 4 lines and 6 points
- Chicago-Lambeth Quadrilateral, a four-point statement of fundamental doctrine, in the Anglican Communion
- Wesleyan Quadrilateral, the four sources of doctrine in the Methodist Church
- Golden Quadrilateral, a network of highways in India
- Quadrilateral Security Dialogue, a strategic alliance of the United States, Japan, Australia and India within Asia.
- Quadrilateral Treaty, a pact between the Argentine provinces of Buenos Aires, Santa Fe, Entre Ríos and Corrientes, signed on 25 January 1822.
- Quadrilatero, in the Revolutions of 1848, in the Italian states - an area within the group of fortresses at Mantua, Verona, Peschiera and Legnago
- Quadrilateral (horse), thoroughbred racehorse