octagonal

American  

[ok-tag-uh-nl] / ɒkˈtæg ə nl /

adjective

1. having eight angles and eight sides.

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octagonal British  

/ ɒkˈtæɡənəl /

adjective

1. having eight sides and eight angles

2. of or relating to an octagon

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Other Word Forms

• octagonally adverb

Etymology

Origin of octagonal

1565–75; octagon + -al ¹, replacing earlier octogonal < New Latin octōgōnālis, equivalent to octō- octo- + Greek gōn ( ía ) angle + -ālis -al ¹

Explanation

Anything that's octagonal has eight sides and eight angles. A stop sign has an octagonal shape, and so may your trampoline You can also call something that's octagonal an octagon. Octagonal buildings may be unusual, but you can find examples of them around the world — there are many churches and cathedrals with octagonal sections, for example. Both octagonal and octagon come from the Greek oktagononos, "eight-angled," from the roots okto, "eight," and gonia, "angle."

Example Sentences

Original plans called for an octagonal building with a grand piano.

From The Wall Street Journal • Dec. 14, 2025

An octagonal tower set over four floors, Draper's Windmill is a special place for Robin Colyer from Kent.

From BBC • Dec. 10, 2025

The octagonal wooden structure dates to 1842, although a lighthouse has been at the site since 1768.

From Washington Times • May 26, 2023

Wong especially taps the tension behind Amy’s exquisite octagonal glasses, the pressure to provide and be perfect — she’s like Rachel Fleishman with a gun instead of yoga.

From New York Times • Apr. 5, 2023

With a courteous bow, he opened for me himself the door to the octagonal room, and I entered my bedroom....

From "Dracula" by Bram Stoker