Are there any letters in the English alphabet that never appear twice consecutively in a word?

For example: the word running has the letter n repeated consecutively in it.

What letters never appear in such way (for example q comes to mind)?

For context, this is asked in relation to "breaking" encrypted messages. Knowing about such letters can help rule out some of the options.

  • 6
    This article would seem related: Which double letters appear most frequently in English text? - especially the section on The frequency of double letters in an English corpus which mentions "Some double letters did not appear in the corpus: JJ, KK, QQ, VV, WW, and YY. " Mar 26, 2021 at 22:21
  • You're new here and also got immediately downvoted for what seems to be a reasonalbe question. Seems like this substack has problems. Mods should really look in to this.
    – Williams
    Mar 27, 2021 at 0:09
  • I’m voting to close this question because I consider it is on the trivia side of the dividing line, being more appropriately asked on Puzzling.SE. Questions on ELU focus on English usage, and should always be accompanied by reasonable research and attempts at answering. Requests for lists are almost always considered off-topic. Mar 27, 2021 at 18:30
  • 1
    @KillingTime Bookkeeper, trekking and sawwort were obviously not included. Mar 27, 2021 at 18:36

1 Answer 1


If I calculate the number of occurrences of double letters in the (about 90 000 words) Mathematica online dictionary (which is not an authoritative dictionary of English because it contains some entries that are proper names), I find the statistics below:

Mathematica online

In this table, the best candidates are qq and xx, which both score zero (xx appears once in Exxon, which is a trade name).

The next is yy with Omayyad, Ayyubid and the proper name Khayyam).

Then we have jj, with various words related to hajj

The subsequent more frequent occurrences are more likely to be found in conventional English dictionaries, where other words may also occur (note doxxing, in Merriam Webster)

enter image description here

  • Doxxing is a word now.
    – Damila
    Mar 30, 2021 at 2:20
  • @Damila yes, language evolves and dictionaries always lag behind. Dox is not in the Mathematica dictionary but is defined in merriam-webster.com/dictionary/dox. I have added your point to the answer.
    – Anton
    Mar 30, 2021 at 6:54

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