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pentagon

pentagon

1 3.0
A flat shape with five straight sides and five angles
  • noun
  • /ˈpɛntəˌɡɒn/
translation icon : pentágono
  • In geometry class, we learned that a pentagon has five sides and five angles.
  • 12 pentagons

Put some powder on the head and then slid around on the floor like a snail and drew a Pentagon and lit a match or a little match.

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Examples

  • Lining its periphery are various display cases of historical interest; and positioned along the wall at each point of the pentagon are five arched niches—each one containing a bronze bust.

    Fiction book (1992)
  • - How many sides does a pentagon have?

  • Pick the next shape in a series: triangle, square, pentagon...?

    Fiction book (1994)
  • Tiles include regular pentagons built with a 3D printer.

    Academic text (2014)
  • Five fold patterns, however, are more challenging to tessellate because pentagons don't neatly fill a surface.

  • The fort was laid out on a pentagon plan with five bastions (1), one at each corner, which gave it its "star" shape, and the main gate was protected by a ravelin (2).

    Blog text (31)
  • The playground features a large pentagon where children can play games.

  • To draw a regular pentagon, make sure each angle measures 108 degrees.

Compounds

242 3.6

A large five-sided building in Arlington where US military leaders work

regular pentagon
  • Specialized
3.7

A five-sided shape with all sides and all angles equal

9.9

A violent group in the Philippines that kidnaps people and takes money by force

How Many Sides

dodecagon
  • Specialized
1 8.2
decagon
  • Specialized
6.7
nonagon
  • Specialized
7.6
octagon
7 3.3
hexagon
5 2.8
pentagon
1 3.0
triangle
58 1.0

Surface Forms

pentagon singular
pentagons plural

Morphology

pentagon = penta + gon

The components penta- ('five') and -gon ('angle') transparently reflect the meaning, but they are Greek combining forms rather than standalone English words, so an average B1 learner may not reliably infer the meaning from the parts.

Etymology

Pentagon comes from Greek parts penta- meaning 'five' and -gon meaning 'angle'. So a pentagon is a flat shape with five angles and five sides, like how a triangle has three.