a plane figure that is bounded by a finite number of straight line segments (sides) joined to form a closed chain or circuit; typically described by its vertices and edges (e.g., triangle, quadrilateral).

平面上の直線の辺が有限個つながって閉じた図形（角と辺をもつ図形）。例：三角形、四辺形

in computer graphics and 3D modelling, a polygon often refers to a flat surface element (usually a triangle or quad) used to build meshes; the term is also used informally to mean a face of a mesh.

コンピュータグラフィックスや3Dモデリングで、メッシュを構成する平面要素（通常は三角形や四角形）。文脈によってはメッシュの面を指す