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Quadrilateral
(noun)

- A flat shape with four sides and four angles.
- A polygon with four sides.
- A figure having four sides, especially a rectangle, a square, a parallelogram, or a trapezium.

### Origin:

Late 16th century: from latin quadrilaterus, from quadri- "four" + later "side".

### Examples:

- The quadrilateral was easily transformed into a parallelogram.
- The area of the quadrilateral was calculated using the formula for a parallelogram.
- The quadrilateral was used as a base for the pyramid.
- The quadrilateral was divided into two congruent triangles.
- The quadrilateral was drawn on the board to demonstrate geometric concepts.