decagon
Americannoun
-
decagons
plural
noun
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Etymology
Origin of decagon
From the Medieval Latin word decagōnum, dating back to 1565–75. See deca-, -gon
Explanation
A decagon is a closed shape with ten sides and ten angles. Your geometry teacher would also tell you that a decagon is a polygon. The word decagon comes from Greek roots, deka, or "ten," and gōnia, "angle or corner." Any ten-sided shape can be called a decagon, whether it's a street sign or the doodle you draw in your notebook during math class. Speaking of math class, in geometry you may learn that a "regular decagon" is one with sides that are all equal to each other and with internal angles that all measure 144 degrees.
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Researchers will continue monitoring Saturn to see whether the southern decagon becomes a stable, long-lived feature like the northern hexagon or keeps changing.
From Science Daily ● Sep. 3, 2026
Ground-based observations collected in 2025 provided stronger evidence that the feature had developed into a decagon.
From Science Daily ● Sep. 3, 2026
Scientists still do not know what triggered the decagon or whether it will remain stable.
From Science Daily ● Sep. 3, 2026
Different wavelengths allow astronomers to observe different altitudes within Saturn's atmosphere, producing small shifts in where the decagon seems to appear.
From Science Daily ● Sep. 3, 2026
Most of the list came from the state eighth grade curriculum: barometer, decagon, perpendicular .
From "Schooled" by Gordon Korman
Of nouns in on, derived from Greek, the greater part always form the plural regularly; as, etymons, gnomons, ichneumons, myrmidons, phlegmons, trigons, tetragons, pentagons, hexagons, heptagons, octagons, enneagons, decagons, hendecagons, dodecagons, polygons.
From The Grammar of English Grammars by Goold Brown
A. Because it has ten sides and ten angles, and there are both regular and irregular decagons.
From The Infant System For Developing the Intellectual and Moral Powers of all Children, from One to Seven years of Age by Samuel Wilderspin
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
