polygon

/ˌpɑliˈgɑn/

/ˈpɒligɒn/

Other forms: polygons

A polygon is a closed shape with straight sides. Rectangles, triangles, hexagons, and octagons are all examples of polygons.

The word polygon comes from the Greeks, like most terms in geometry, which they invented. It simply means many (poly) angles (gon). A polygon can’t have any curves or any gaps or openings in its shape. If you want to describe something as angular and closed, like, say, the Pentagon, or a stop sign, you could call it "polygonal."

Definitions of polygon

1. noun

   a closed plane figure bounded by straight sides
   synonyms: polygonal shape

   types:

   isogon

   an equiangular polygon

   convex polygon

   a polygon such that no side extended cuts any other side or vertex; it can be cut by a straight line in at most two points

   concave polygon

   a polygon such that there is a straight line that cuts it in four or more points

   quadrangle, quadrilateral, tetragon

   a four-sided polygon

   triangle, trigon, trilateral

   a three-sided polygon

   pentagon

   a five-sided polygon

   hexagon

   a six-sided polygon

   heptagon

   a seven-sided polygon

   octagon

   an eight-sided polygon

   nonagon

   a nine-sided polygon

   decagon

   a polygon with 10 sides and 10 angles

   undecagon

   an eleven-sided polygon

   dodecagon

   a twelve-sided polygon

   spherical polygon

   a figure on the surface of a sphere bounded by arcs of 3 or more great circles

   reentering polygon, reentrant polygon

   a polygon with one or more reentrant angles

   regular polygon

   a polygon with all sides and all angles equal

   acute triangle, acute-angled triangle

   a triangle whose interior angles are all acute

   equiangular triangle, equilateral triangle

   a three-sided regular polygon

   isosceles triangle

   a triangle with two equal sides

   oblique triangle

   a triangle that contains no right angle

   obtuse triangle, obtuse-angled triangle

   a triangle that contains an obtuse interior angle

   right triangle, right-angled triangle

   a triangle with one right angle

   scalene triangle

   a triangle with no two sides of equal length

   parallelogram

   a quadrilateral whose opposite sides are both parallel and equal in length

   trapezium

   a quadrilateral with no parallel sides

   trapezoid

   a quadrilateral with one pair of parallel sides

   regular hexagon

   a hexagon with six sides of equal length

   spherical triangle

   a spherical polygon formed by the arcs of 3 great circles

   cuneus, wedge, wedge shape

   any shape that is triangular in cross section

   type of:

   plane figure, two-dimensional figure

   a two-dimensional shape