A quadrilateral, in geometry, is a polygon with 4 sides.

Quadrilateral may also refer to:

• "Quadrilateral", an alternative name for Southern Dobruja, an area of north-eastern Bulgaria mostly used by Romanians
• Quadrilatero, in the 1848 revolutions, in the Italian states, an area within the group of fortresses at Mantua, Verona, Peschiera, and Legnago

• 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.

• 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

• Complete quadrilateral, in projective geometry, a configuration with 4 lines and 6 points
• Golden Quadrilateral, a network of highways in India
• Quadrilateral (horse), thoroughbred racehorse
• Quadrilateral (film), a 2024 Peruvian film

• Quadriliteral
• Quadrangle (geography)