In all forms of Latin I know, the letter Q is always followed by a U. No other letter seems to be bound this way. The combination QU stands for something like /kw/, and it would make more sense to me to let the letter Q alone stand for /kw/ and absorb the letter U into it since they always come together. This would not be the only letter to stand for two sounds; consider X. The only point in the letter Q seems to be that it signifies that the following U is consonantal, as opposed to C whose following U seems to be always vocalic. For example, consider the difference between qui and cui. This makes Q look like a special case of C, but weirdly so, as it only modifies the pronunciation of a following U, not the C itself.

What is the origin of the letter Q? Why does it behave in such a weird way, always requiring a U? Why do we need the letter (in its current form) in the first place? Can the origins of Latin pronunciation or alphabet shed some light on the unusual behavior of Q? In short: What's the deal with Q?

  • 1
    The answer to Where can I hear the original pronunciation of the Latin alphabet? has some relevant information
    – Asteroides
    Oct 8, 2017 at 19:31
  • @sumelic Thanks for pointing that out! I had forgotten about it. It is certainly relevant.
    – Joonas Ilmavirta
    Oct 8, 2017 at 19:48
  • I'd almost want to say that that answer makes this redundant.
    – cmw
    Oct 8, 2017 at 20:33
  • @C.M.Weimer The answer to this question might be contained there, but the questions are very different. An abridged version of that other answer focusing on Q would be good here. But this is just my opinion; I will leave it for others to vote and decide whether this question is a duplicate.
    – Joonas Ilmavirta
    Oct 8, 2017 at 21:03
  • 1
    Related (including the comments) linguistics.stackexchange.com/questions/6767/…
    – Alex B.
    Oct 9, 2017 at 3:14

2 Answers 2


This answer already gave the answer as pointed by sumelic.

In short, in archaic Latin, there were three letters 𐌂, 𐌊, and 𐌒, corresponding to C, K and Q. All those letters were used for both the sound /k/ and /g/. Later the letter G was used for the sound /g/ so C was the only letter for /k/. The letter K became rare and remained only before /a/ (Kalenda…) and Q, which was used in Etruscan before rounded vowels /kʷ/, remained only before /u/ and was therefore only conserved in QV.

Cf. also Wikipedia:

The Etruscans used Q in conjunction with V to represent /kʷ/, and this usage was copied by the Romans with the rest of their alphabet. In the earliest Latin inscriptions, the letters C, K and Q were all used to represent the two sounds /k/ and /ɡ/, which were not differentiated in writing. Of these, Q was used before a rounded vowel (e.g. ⟨EQO⟩ 'ego'), K before /a/, and C elsewhere. Later, the use of C (and its variant G) replaced most usages of K and Q: Q survived only to represent /k/ when immediately followed by a /w/ sound.

  • In the Semitic languages which Greek was derived from, K and Q had (and still have!) different pronunciations, and neither is necessarily followed by U - for example the names of the letters themselves as "kaaf" and "qaaf". Somewhere along the line, things got simplified. FWIW the modern English "q" and "k" sounds both correspond to modern Arabic "k" and not to "q" which doesn't have an equivalent sound in English
    – alephzero
    Oct 12, 2017 at 4:33
  • ... and also, a single Arabic letter ("waaw") is used both for the English "w" and long "u" (or "oo") sounds.
    – alephzero
    Oct 12, 2017 at 4:40
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    @alephzero. I think you are confusing languages and scripts. Greek is not derived from "Semitic languages".
    – fdb
    Oct 14, 2017 at 15:05
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    Can you add a screenshot of those three archaic Latin letters? On some computers they show up as boxes. (I doubt all three letters were denoted by a box.)
    – Joonas Ilmavirta
    Oct 16, 2017 at 13:55

From a synchronic point of view, the retention of Q as an allograph of C had the advantage that it disambiguates the distinction of the very common words QVI (qui) and CVI (cui), which would otherwise be homographs.

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