pentagonal

adjective

pen·​tag·​o·​nal pen-ˈta-gə-nᵊl How to pronounce pentagonal (audio)
1
: having five sides and five angles
2
: having a pentagon as a cross section or as a base
a pentagonal pyramid
pentagonally
pen-ˈta-gə-nᵊl-ē How to pronounce pentagonal (audio)
adverb

Examples of pentagonal in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Interestingly, though, pentagonal arrangements of atoms can fill space in almost-but-never-quite-repeating patterns with fivefold symmetry, forming materials called quasicrystals. — Natalie Wolchover, Quanta Magazine, 10 Aug. 2026 The quadrilateral, pentagonal and hexagonal cases all obey this formula, but no larger shapes have been confirmed. — Jack Murtagh, Scientific American, 10 Aug. 2026 The theater is made up of 316 individual hexagonal and pentagonal shapes in 16 different sizes. — Anthony D'alessandro, Deadline, 21 July 2026 These limbs are positioned according to a regular dodecahedral geometry, a structure defined by 12 pentagonal faces, producing a highly uniform distribution of both force and visual coverage. — Jijo Malayil, Interesting Engineering, 27 May 2026 See All Example Sentences for pentagonal

Word History

First Known Use

1571, in the meaning defined at sense 1

Time Traveler
The first known use of pentagonal was in 1571

Rhymes for pentagonal

See All Rhymes for pentagonal

Browse Nearby Words

Pentagon
pentagonal
pentagon crab
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Cite this Entry

“Pentagonal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/pentagonal. Accessed 18 Aug. 2026.

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Kids Definition

pentagonal

adjective
pen·​tag·​o·​nal pen-ˈtag-ən-ᵊl How to pronounce pentagonal (audio)
1
: having five sides and five angles
2
: having a pentagon as a cross section or as a base
a pentagonal pyramid

More from Merriam-Webster on pentagonal

Nglish: Translation of pentagonal for Spanish Speakers

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