octagonal

American  

[ok-tag-uh-nl] / ɒkˈtæg ə nl /

adjective

1. having eight angles and eight sides.

---

octagonal British  

/ ɒkˈtæɡənəl /

adjective

1. having eight sides and eight angles

2. of or relating to an octagon

---

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

Of all the historical monuments in Puglia, it is the inland landmark of Castel del Monte, a hilltop octagonal castle, that has become a national symbol, finding its way onto stamps and money.

From The Wall Street Journal • Oct. 26, 2025

Some of the findings are "unique" for South America, he explains, pointing to the octagonal and rectangular platforms arranged together.

From BBC • Jan. 11, 2024

In the decades following the publication of “The Octagon House: A Home for All,” octagonal homes “broke out in New York State like a rash,” as an article in this newspaper put it.

From New York Times • Aug. 11, 2023

The sword, featuring a distinct octagonal hilt, was so well-preserved by the elements in the millennia since it was buried that it still has a shine and sheen.

From Washington Times • Jun. 16, 2023

All mitered cuts because, he announced, The Amazing Deck would be octagonal.

From "Please Ignore Vera Dietz" by A.S. King