Consonant mutations are a strong characteristic of the Celtic languages. An example in Breton would be:

Khaz /kaz/: cat
Ar c'haz /aʁ.xaz/: the cat

The /k/ is altered to /x/ after ar.

According to Wikipedia there are mutations in Russian, but I am not familiar with the process. Are these similar to the Celtic mutations or a completely different thing? Where do the Celtic ones come from? Is it a peculiarity of Celtic languages, or could it be traced back in others, maybe ancient, Indo-European groups?

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    If this is some form of assimilation or dissimilation, and if we will consider word boundaries non-essential, it is a common phenomenon in many IE languages. But I don't know anything about this particular kind of change in Celtic (in fact, I don't know anything about Celtic.)
    – Cerberus
    Commented Sep 14, 2011 at 0:17
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    This hits on the topic of the history of the initial mutations within the Celtic languages. uni-due.de/~lan300/13_Initial_Mutation_in_Celtic_(Hickey).pdf Commented Jan 8, 2014 at 16:17
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    You might want to read Stefan Zimmer’s article as well, The Celtic Mutations: some typological comparisons. Commented Dec 7, 2014 at 19:58
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    French liaison is a similar or arguably opposite phenomenon (like English an vs a). In Slavic languages there are many consonant mutations of final sounds in stems among morphological variants (eg Amerika vs Americi or momak vs momče in Serbo-Croatian). These are all very superficial - they have no grammatical meaning and vary among related languages. To me this suggests that they are relatively recent innovations and if ancient then coming from the accent of local groups that were assimilated. Commented Oct 31, 2015 at 13:50

5 Answers 5


Something similar shows up in some of the Italian dialects. The relevant dialects are the ones with the following two features:

1) The Gorgia Toscana: After a vowel, p, t and k go to [ɸ], [θ] and [h]. This happens even when the triggering vowel is in the preceding word: la casa is [la'hasa] in dialects with this feature. But it only affects single p, t and k, not the geminate consonants pp, tt and kk.

2) Syntactic doubling: There are some specific words that, idiosyncratically, trigger gemination on the first consonant of the following word. This has the effect of blocking the preceding sound change. So a casa is [ak'kasa], and not [a'hasa].

If a Celticist were describing this sort of Italian they might say it had two mutation classes. Some words trigger "lenition" or "spirant mutation," others trigger "hard mutation."

If I understand correctly, there are even minimal pairs of words that only differ in which mutation they cause. So for instance, the clitic pronoun si doesn't trigger fortition, but the particle , meaning "if," does. This is a little like how, in Irish, a means "his" if it's followed by lenition, and "hers" if it isn't. The Italian examples are not as dramatic as the Irish ones, though — my perception is that there are a lot fewer minimal pairs like this in Italian.

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    The wikipedia article on Sardinian describes a process where, for example, "porku (pig) but su borku (the pig); domo (house) but sa omo (the house)" (examples from en.wikipedia.org/wiki/Sardinian_language)
    – jogloran
    Commented Feb 26, 2012 at 12:11

Wikipedia, quoting Temes, Elmar, 1986, writes:

Historically, the Celtic initial mutations originated from progressive assimilation and sandhi phenomena between adjacent words. For example, the mutating effect of the conjunction a 'and' is due to the fact that it used to have the form *ak, and the final consonant influenced the following sounds

There are sandhi and sandhi-like phenomena in other IE languages (French for example), and this specific consonant mutation in celtic languages (which is called lenition) can be found in other IE languages. However, there are multiple types of lenition:

  • diachronic - a lenition that has happened historically - a consonant was strong in Latin, but has weakened in Italian, for example
  • synchronic - the change happens in the present form of a single language. Such, according to Wikipedia, happens in Western Romance languages in addition to Celtic languages, although it does not bear grammatical meaning as in Celtic ones.

A similar phenomenon to Irish eclipsis exists in Modern Greek, although more limited in terms of the number of consonants it applies to. According to Wikipedia's article on "Modern Greek Phonology":

[when a word beginning with a voiceless stop follows] a number of grammatical words ending in /n/, most notably the negation particles δεν and μην and the accusative forms of the personal pronoun and definite article τον and την [..] /n/ either assimilates for place of articulation to the stop, or is altogether deleted, and the stop becomes voiced. This results in pronunciations such as τον πατέρα [to(m)baˈtera] ('the father') or δεν πειράζει [ðe(m)biˈrazi] ('it doesn't matter'), instead of *[ton paˈtera] and *[ðen piˈrazi]. The precise extent of assimilation may vary according to dialect, speed and formality of speech.


There are consonant alternations in Russian but they work in a somewhat different way than in Celtic, and therefore I'm not sure that it's a good idea to call them the same name, mutation. In short and off the top of my head,

  1. Celtic mutations happen in anlaut and are petrified sandhi phenomena which may, at least in some cases, be the only carriers of morphological information nowadays (see the use of the Irish article an).
  2. Russian (Slavonic) alternations happen on morpheme boundaries, are a by-product of regular sound changes and can't carry morphological information on their own. Examples from Polish:

    kot 'cat' + -e praep., voc. > koci.e [koće], e.g. in *o kocie* '1. about a cat; 2. oh [my] cat!'
    krok 'step' + -ek dimin. > krocz.ek [kroček] 'a small step'
    mnich 'monk' + -i pl. > mnisi [mńiśi] 'monks'
    rzek.a 'river' + -e praep. > rzec.e [žece], e.g. in *w rzece* 'in the river*
    wag.a 'scales' + -e praep. > wadz.e [vaʒe], e.g. in *na wadze* 'on the scales'

Hebrew is not strictly Indo-Eurpoean (although some argue it is), but it has something similar: the fricatives /v/, /χ/ and /f/ (when represented by the letters ב, כ and פ) become the plosives /b/, /k/ and /p/ when they come at the start of the word, or after some prepositions, but not after other prepositions. This is called a Dagesh Kal.

For example,

כּלב kelev: dog

הכּלב hakelev: the dog


לכלב leχelev: for/to a dog

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    Hebrew is a Semitic language, the personal opinion you cite is not widely accepted.
    – Louis Rhys
    Commented Sep 14, 2011 at 6:37
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    There are in fact those who are trying to force an analysis dividing "Hebrew" and "Israeli Hebrew" by overemphasising modern language's influence from European languages. So while not widely accepted the opinion is far from being a solitary one. It might make a good separate question. Commented Sep 14, 2011 at 8:21
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    @hippie: asked here
    – Louis Rhys
    Commented Sep 14, 2011 at 8:53
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    As for the source of this feature, the "original" Hebrew (from the Bible days) didn't have a diacritic to reflect it. The Dagesh, along with the rest of the Niqqud, was developed in the early middle ages (see en.wikipedia.org/wiki/Niqqud). However, this phonological feature probably existed long before it was reflected in writing, so it is correct to assert that this is not related to the Indo-European phenomenon (although there has been Indo-European effect on Hebrew long before the modern time). Commented Sep 14, 2011 at 19:25
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    The phonological process is actually the opposite of that described in this answer: certain stops spirantize after a vowel (not 'certain fricatives become stops word-initially'). This was regular in earlier stages of Hebrew, but is no longer regular in the modern language. It's not very similar to Celtic mutation because it's purely phonologically conditioned and isn't limited to initial consonants.
    – TKR
    Commented Oct 30, 2013 at 23:06

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