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[dek-uh-gon, -guh n]
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noun Geometry.
  1. a polygon having ten angles and ten sides.
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Origin of decagon

From the Medieval Latin word decagōnum, dating back to 1565–75. See deca-, -gon
Related formsde·cag·o·nal [duh-kag-uh-nl] /dəˈkæg ə nl/, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words


Examples from the Web for decagon

Historical Examples

  • The plan of the church was a decagon, within which six composite columns in the centre supported six semi-circular vaults.

    Old and New London

    Walter Thornbury

  • Decagon, dek′a-gon, n. a plane figure of ten angles and sides.

  • In the fourth are six triangles, in the fifth, five polygons from a pentagon to a decagon.

    The Montessori Method

    Maria Montessori

  • Below the arches are the chapels which surround the decagon in symmetrical fashion.

British Dictionary definitions for decagon


  1. a polygon having ten sides
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Derived Formsdecagonal (dɪˈkæɡənəl), adjectivedecagonally, adverb
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for decagon


early 17c., from Modern Latin decagonum, from Greek dekagonon, from deka "ten" (see ten) + gonia "corner, angle" (see knee (n.)).

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Online Etymology Dictionary, © 2010 Douglas Harper

decagon in Science


  1. A polygon having ten sides.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.