The close-mid back rounded vowel is usually diphthongized to [oʊ] or [əʊ] in North America and respectively, Britain.

Examples: row, also.

In fact, in the Cambridge English Pronouncing Dictionary I didn't see o standing by itself.
In some other languages, you can pronounce it just by itself. How common is that and why is English different?

4 Answers 4


English high and mid non-central vowel phonemes fall into two categories:

  1. tense /i e o u/
  2. lax /ɪ ɛ ɔ ʊ/

Beside the tense/lax phonetic distinction (which refers to the muscles at the root of the tongue), these phonemes are distinguished in several other ways -- language loves redundancy and builds it into the structure whenever possible.

For instance, all the tense vowel phonemes are diphthongized, whereas the lax vowels are pure vowels, which may be neutralized with their tense counterpart in some environments (Mary, merry, marry), but never appear with an offglide except in local variants.

In the high vowels /i, u/ the diphthongization isn't always distinctive because the tongue gesture is so short, but it's there and shows up in transitional /y/s and /w/s in phrases like be able or do it. It's clearer in the mid vowels, where the distance the tongue has to move going from [e] to [i] or [o] to [u] is longer and more easily distinguished.

Indeed, pronunciation of Spanish /e/ as /ei/ and /o/ as /ou/ is one of the characteristics of an English accent. English speakers are normally unable to distinguish the two in Spanish, just as Spanish speakers are normally unable to distinguish English tense vowels from lax, leading to ship sheep late let Paul pole foot boot vocabulary problems.

There are complexities. In RP, as noted, the actual diphthong is centralized to [əʊ], and the Northern Cities Chain Shift has screwed up urban American English vowels almost as thoroughly as what the Great Vowel Shift did to Middle English vowels.

  • I think final vowels are never short, such as in limbo, libido, flambe, emigre, apriori, alumni etc. Maybe this is related to a late consequence of Great Vowel Shift, since these words look like late borrowings from other languages. Commented Jan 17, 2014 at 15:57
  • I reread your post and y is short in merry/Mary/marry Commented Jan 18, 2014 at 1:11
  • 1
    There isn't any y in those words. They end in /i/. We're talking about pronunciation, not spelling. And English hasn't had distinctive long vowels since the Great Vowel Shift, when the long vowels diphthongized and the short vowels didn't.
    – jlawler
    Commented Jan 18, 2014 at 3:43
  • Why do you describe the diphthongization of tense vowels as distinctive and write it with slashes?
    – Greg Lee
    Commented Aug 20, 2015 at 19:26
  • 1
    @BogdanLataianu At least for American English, the fact that “short” vowels never end words is way more important than the fact that they are “short,” because vowel length is pretty much irrelevant here. The only sensible distinction between vowel phonemes you can make for my accent (GenAm with mild Inland North features) is checked vs free - not long vs short, diphthong vs monophthong, or tense vs lax (those last two being probably the most opaque terms in all of phonetics).
    – Graham H.
    Commented Jul 22, 2023 at 0:40

In British English, actually, the diphthongization is [əʊ], while [oʊ] is more US pronunciation.

English doesn't have a single [o] in words, because it's a short vowel and English doesn't have a short "o" sound. The case where it's not followed by [ʊ] is [ɔ:], as in caught.

If you look at this page about English Phonology, and you look at the table reporting the vowels in English, you'll see that the box for "mid back short" is empty.

  • Indeed, I was talking about US English. Commented Dec 1, 2011 at 18:51
  • 1
    @Theta30 You mentioned the Cambridge English Pronouncing Dictionary though. :)
    – Alenanno
    Commented Dec 1, 2011 at 19:11
  • 1
    That dictionary shows US pronunciations too Commented Dec 1, 2011 at 19:12
  • In the IPA Handbook, Ladefoged doesn't have [ɔ] in his vowel chart for American English.
    – Alex B.
    Commented Dec 1, 2011 at 19:26
  • 1
    @Theta30 I don't know every dictionary, if you don't specify I am not able to know that. Alex, I was trying to look for a word with [ɔ] but wasn't able to find anything. I originally thought about it, but when I saw that in that chart it wasn't available AND that I couldn't think of any word with it, I thought I was wrong... :)
    – Alenanno
    Commented Dec 1, 2011 at 19:37

At first, you misquoted Wikipedia. What it actually says (the current edit) is that "in the north of the Netherlands and in North Central American usually diphthongized to [oʊ]." The same Wikipedia article has lots of examples when it "stands just by itself."

In British English, things are way more complicated. Although [əʊ] is the most common variant now, there are other variants, too; see part 8.10.4 in Gimson's Pronunciation of English (7th ed.).

And there are British dialects where [o:] is not diphthongized. After all, in Middle English it wasn't, either. It got diphthongized during the Great Vowel Shift. There are dialects where the glide is a schwa etc.

For some discussion based on the material of English dialects (the so called goat test), see Wells, J. C. 1981. Accents of English. Cambridge: CUP.

In The Linguistic atlas of England, you can find excellent maps; see, for example, the word "oak" (or loaf, toad etc.), which is not diphthongized in some dialects.

  • Actually he didn't misquote it. If you look at the table at "English -> North Central American -> «row»", you'll see his quote in the last column.
    – Alenanno
    Commented Dec 1, 2011 at 18:35
  • didn't see it at first, thanks!
    – Alex B.
    Commented Dec 1, 2011 at 19:03
  • It got diphthongized during the Great Vowel Shift? What? Every resource I’ve seen discusses the raising of the GOAT vowel from historical [ɔː] to [oː] as an element of the Great Vowel Shift, while none discuss the diphthongization of that vowel in many accents. That’s a completely separate and much later development.
    – Graham H.
    Commented Jul 22, 2023 at 0:43
  • @GrahamH. Let me know how you interpret Minkova 2014 A historical phonology of English, pp. 264-265
    – Alex B.
    Commented Jul 22, 2023 at 21:31

The map of North American English Dialects has vast amount of collected data pertaining to your topic, with a visually appealing presentation.

  • so there's more to the story, since they speak about front vowels, and none of [o], [ʊ] or the schwa is a front vowel. Commented Dec 3, 2011 at 13:58

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