When Latin evolved to French, the vowel /u/ fronted to become /y/... except in Latin "VRSVS" /ur.sus/ > French "ours" /uʁs/, in which the vowel /u/ was kept.

I do not think that the /rs/ environment kept the /u/, because we can see Latin "DVRVS" /du.rus/ > Old French "durs" /dyrs/, where the "u" is changed anyway.

Usually, front vowels tend to be unrounded and back vowels tend to be rounded, but this sound change seems to have violated this rule.

I am aware that probably there is no answer as to what exactly caused the fronting and the "VRSVS" exception, but mere guesses would be fine for me, as such sound change violates the rule that front vowels tend to be unrounded.

2 Answers 2


The question does not accurately summarize the relevant sound changes. Latin short /u/ was not fronted to /y/. Only Latin long /uː/, as in dūrus /duːrus/, regularly developed to /y/ in French. (Of course, in learned words such as dubitatif, Latin U corresponds to /y/ regardless of its original length, but this does not represent a regular phonetic development.)

As a rule, Latin short /u/ (as in ŭrsus) merged with the reflex of Latin long /oː/ in French. The distinction between the reflexes of Latin /u/ and /uː/, with a merger of the reflexes of Latin /u/ and /oː/, is a common feature of the "Italo-Western" Romance languages. For comparison, Italian duro and orso also have different vowels.

Based on these reflexes, we can reconstruct a "Proto-Italo-Western-Romance" (PIWR) vowel system that distinguished vowel height but not length and had Latin /uː/ > PIWR *u and Latin /u/, /oː/ > PIWR *o.

  • PIWR *u became fronted to /y/ in the Old French period, and "u" /y/ is the usual reflex in Modern French.

  • PIWR *o developed differently; in Modern French the reflex is either "eu" (/ø/, /œ/) or “ou” (/u/). In Old French, it seems /u/ could be spelled as "o," "u" or "ou". In general, we get "eu" in stressed syllables that were open (during some particular stage of the language), and “ou” elsewhere, but there are other factors that make the distribution more complicated such as paradigmatic leveling and dialect mixing. We definitely would not expect ours to have /y/.

Wikipedia has an article "Phonological history of French" that may not be entirely accurate but that presents a general overview of the situation.

As for why/how the fronting occurred: I don't have any answer, sorry. All I can offer is some similar changes in other languages, such as Greek (where ancient /u/ became Classical Greek /y/) and modern English (where /u/ is often fronted more or less, depending in part on the phonetic environment).

A bit of Googling turned up the following paper: "The Feature [Advanced Tongue Root] and Vowel Fronting in Romance," by Andrea Calabrese.

Calabrese says

Previous explanations of this change [that is: /u/ > [y]], based on substratum theory (Ascoli 1881) and structural pressure due to independent sound changes, besides being outdated, are quite unsatisfactory. There is no generative study of this change, and it is usually considered to be an 'unnatural' sound change that defies explanation (cf. Dressler (1974)).

I guessed that it was connected to the sound change /o/ > /u/, but the first sentence says that is not likely to be relevant. Calabrese goes on to propose an explanation based on the feature [advanced tongue root], which is illustrated by examples of a similar sound change in the southern Italian dialect of Altamura; I don't fully understand it so I won't copy it here, but you can look in the paper at section 4, page 84 to see what she says about Old French.

  • Thanks for your answer. 1: My question is mainly how Proto-Romance /u/ became fronted to Modern French /y/, from a phonological point of view, which you did not answer. 2: Also, your linked article has an answer to your question, that the /o/ in a closed environment developed to "ou" /u/. 3: However, en.wikt says that the word is spelt "urs" in Old French, which indicates /u/ instead of /o/ I believe.
    – Kenny Lau
    Commented Aug 20, 2016 at 5:06
  • Follow-up to your edit: I did say that "I am aware that probably there is no answer as to what exactly caused the fronting [...] but mere guesses would be fine for me"
    – Kenny Lau
    Commented Aug 20, 2016 at 5:20
  • Another follow-up: can you elaborate on "I believe it was part of a chain shift where modern French /u/ became established by the raising of former /o/"?
    – Kenny Lau
    Commented Aug 20, 2016 at 5:27
  • I assume that I would have to go through the whole paper just to understand what is said about Old French... I'll do that when I have the time to.
    – Kenny Lau
    Commented Aug 20, 2016 at 6:50
  • 1
    My understanding is that the u: / u difference is not proto-Romance, because Sardinian simply shortens cowels and i,i>i,u, not e,o.
    – user6726
    Commented Feb 2, 2019 at 20:15

Your question seems to be made of two questions. Q1 is about the outcome of Latin u/u: in French. Q2 is about ü [y] versus u or i. Implicational universals have it that a language with ü should first have u or i. There is no language with ü and i but no u, u and ü but not i. This is how "tend to" should be handled.

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