I was wondering if anyone knew of a language (real or fictional!) that did not contain any double consecutive letters (like the double t in "letters").


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    Mandarin in pinyin.
    – user6726
    Jun 23 '18 at 14:57
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    @user6726 what about intra-word, incidental repetition between final and initial, as in Zhōngg or nnián? Jun 23 '18 at 15:21
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    @jlawler, this is about spelling - but not English spelling, because clearly that does have double letter combinations. I think it's on topic based on other questions I have seen here (orthography is not strictly a subset of linguistics but it is related)
    – Trimble52
    Jun 23 '18 at 18:28
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    My guess is that if you actually run a check over a real corpus, there will always be some, because of Roman numerals and loan words or named entities or abbreviations. Jun 25 '18 at 10:52
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    @AdamBittlingmayer: "Serbian: An Essential Grammar", by Lila Hammond, gives "najjači" as an exception to the general absence of double letter sequences in Serbian orthography. Sep 18 '19 at 23:11


Many languages don't allow consonants at the ends of syllables, which means that two of the same consonant will never be next to each other by chance.

Of these languages, some have long/geminate vowels/consonants, or the same vowel twice in a row, and write that with double letters (e.g. Japanese written in Roumaji). So those are no good.

Others either write their geminates differently, like Māori (Polynesian, uses macrons), or don't have length contrasts, like Lingála (Bantu). So those will work for you.

EDIT: Māori may actually have double vowels sometimes! See the comments for details. The point about Lingála stands.

  • 2
    Languages that don't have coda consonants might still have heterosyllabic sequences of the same vowel. I don't know Maori, but it seems to have words written with "aa" like "whakaaraara". Jun 23 '18 at 23:09
  • @sumelic There's some disagreement still about the orthography, but the most official one (used by the local government) spells that "whakārāra" with macrons instead of double vowels. (Or "whakärära" if you're stuck with pre-Unicode codepages, which are still unfortunately common.)
    – Draconis
    Jun 24 '18 at 2:44
  • @sumelic (That said, added a note about vowel sequences)
    – Draconis
    Jun 24 '18 at 2:44
  • I guess that page also seems to say that "whakaako" has a long vowel, so maybe /aa/ coalesces to /a:/ in Maori? I found a paper that says "In Maori, sequences of double vowels may be realized for the same word as a double articulated vowel, a long vowel, or two vowels separated by a glottal stop." (The Phonetic Nature of Niuean Vowel Length, Nicholas Roll, p. 16) Jun 24 '18 at 2:55
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    Lingala seems to have at least one word written with two of the same vowel letters in sequence: "ee", meaning "yes". Sep 18 '19 at 2:25

First, let's distinguish between double letters that function as digraphs indicating a single sound (like English "oo" in "flood", which corresponds to the single vowel phoneme /ʌ/, or "dd" in "middle", which corresponds to the single consonant phoneme /d/), and double letters that arise from the incidental repetition of the same sound without any intervening sounds.

There are many languages with writing systems that don't make use of double consonant letters as digraphs. And as Draconis pointed out, many languages don't allow consonants at the ends of syllables, which would prevent double consonant letters from arising incidentally.

But it's harder to figure out whether a language can never have consecutive vowel letters. Double vowel letter digraphs are fairly common as symbols for long vowels. And aside from that, many languages allow vowel-initial syllables, which brings up the possibility of double vowel letters arising incidentally from a sequence of the same vowel in adjacent syllables. (Languages that forbid that kind of situation often resolve the illegal vowel sequence by turning it into a long vowel, which as mentioned might be written with a double vowel digraph.)

If you include sequences of letters separated by a space, that would cause further difficulties, because languages often either don't have or don't write sound changes that eliminate vowel-vowel sequences across word-space boundaries.

If you don't include sequences of letters separated by a space, I think Vietnamese might qualify, because of the general practice of writing a space between all of the syllables in a Vietnamese sentence, regardless of word grouping. In the linked Wordreference thread, the original poster asked if mặttrời would be an acceptable spelling of mặt trời, and was told to use the spaced spelling.

As far as I can make out from the Wikipedia article on Vietnamese spelling, a doubled letter shouldn't be possible in a single written syllable of Vietnamese. Vietnamese does have a diphthong written "ưu", which might look like a double letter to an English speaker, but ư and u are considered to be separate letters of the Vietnamese alphabet.


Old Church Slavonic is another language with strictly open syllables.

Exceptions might be some foreign words. The dictionary (Cejtlin, Večerka, Bláhová, 1994) has both елинъ and еллинъ (and also елиньнъ) - Greek.


Latvian and Hebrew do not allow double consonants. Even when mentioning names of people from other languages they will drop the second consonant. Thus Wasserman becomes Waserman in both languages. Any other languages with this property?

  • 4
    As for Hebrew there are words like הללויה. But your point about Latvian might still stand. I don't know enough Latvian to say.
    – OmarL
    Nov 14 '20 at 19:40
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    The claim on Latvian is wrong. Skimming a random page on the Latvian Wikipedia I encountered the word sauss with double s at the end. Nov 14 '20 at 22:54
  • 2
    Another nice Lativan word with a double consonant in the middle: galvassāpes "headache". Nov 14 '20 at 23:03

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