What is the term for a polygon that has 3 sides?

A polygon with three sides is known as a triangle. This term is derived from the Greek words "tri," meaning three, and "angle," referring to the corners or vertices of the shape. Triangles are characterized by having three sides and three angles, distinguishing them from other polygons that have a different number of sides.

For example, a quadrilateral has four sides, a pentagon has five sides, and a hexagon has six sides. Therefore, among the terms provided, the triangle uniquely fits the definition of a polygon with three sides.