ngonal

Ngonal is an adjective used in geometry to describe a polygon with n sides, where n denotes a natural number greater than or equal to 3. The term provides a neutral, variable descriptor for polygons in mathematical statements and formulas that are intended to apply to any n-gon.

In practice, 3-gonal polygons are triangles, 4-gonal polygons are quadrilaterals, and 5-gonal polygons are pentagons. The general term is common in formal descriptions such as “an n-gonal polygon” or “an n-gonal prism,” where the exact value of n may be specified later or treated as a variable. The ngonal notation is frequently used in geometry, combinatorics, tiling theory, and graph theory to express properties that depend on the number of sides.

Etymology and usage: The suffix -gonal derives from Greek gonia, meaning angle or corner, and the prefix n is a variable denoting the number of sides. The combined form “n-gonal” is a standard, systematic way to refer to polygons with a specified but unspecified number of sides; it coexists with traditional polygon names such as triangle, quadrilateral, and pentagon. While ngonal is precise and widely understood in formal contexts, everyday discussions typically favor the conventional names for specific polygons.