pentaphthong

pentaphthong noun: a sequence of five vowels pronounced as, or almost as, a single syllable.

Noun

pentaphthong (plural pentaphthongs)

(rare) A sequence of five vowels pronounced as, or almost as, a single syllable.
- Fifty-six diphthongal combinations may be made from the eight vowel elements, four of which, though, we find to be necessarily triphthongs, two tetraphthongs, and one a pentaphthong.1866, Caleb Bates Josselyn, Elements of Pronunciation […], page 53
- Try saying the Dutch word Leeuwen some time. At least a pentaphthong...1992 February 4, Graham Toal, “Vowel Raising Before Nasals”, in bit.listserv.words-l (Usenet)

Coolidge ( a Vermonter) pronounced the vowel in "cow" as a pentaphthong.1993 December 23, Bob Simmonds, “Seamed phthongs”, in bit.listserv.words-l (Usenet):
So what we have here is a pentaphthong: ui@iu.2008 June 17, Ruud Harmsen, “British English "Joshua is"”, in sci.lang (Usenet):

plural	pentaphthongs

From penta- + -phthong, by analogy with diphthong, triphthong.

What does pentaphthong mean?: Pentaphthong means a sequence of five vowels pronounced as, or almost as, a single syllable.
How do you use pentaphthong in a sentence?: Coolidge ( a Vermonter) pronounced the vowel in "cow" as a pentaphthong.
What part of speech is pentaphthong?: Pentaphthong is a noun.
What is the plural of pentaphthong?: The plural of pentaphthong is pentaphthongs.

Adapted from Wiktionary: pentaphthong (page history and authors). Text available under the Creative Commons Attribution-ShareAlike 4.0 license. Word.ws reformatted the entry and added links. Wiktionary data of 2026-09-02.

Last updated: 2026-09-02

Pronunciation audio from Wikimedia Commons, each file under its own free license: LL-Q1860 (eng)-Knabrupt-pentaphthong.wav.

Cite this entry: “pentaphthong.” Word.ws, https://word.ws/pentaphthong. Based on Wiktionary, CC BY-SA 4.0.