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Consonant mutation is change in a consonant in a word according to its morphological or syntactic environment.

Mutation occurs in languages around the world. A prototypical example of consonant mutation is the initial consonant mutation of all modern Celtic languages. Initial consonant mutation is also found in Indonesian or Malay, in Nivkh, in Southern Paiute and in several West African languages such as Fula. The Nilotic language Dholuo, spoken in Kenya, shows mutation of stem-final consonants, as does English to a small extent. Mutation of initial, medial and final consonants is found in Modern Hebrew. Also, Japanese exhibits word medial consonant mutation involving voicing, rendaku, in many compounds. Uralic languages like Finnish show consonant gradation, a type of consonant mutation.

Similar sound changes

Initial consonant mutation must not be confused with sandhi, which can refer to word-initial alternations triggered by their phonological environment, unlike mutations, which are triggered by their morphosyntactic environment. Some examples of word-initial sandhi are listed below.

Sandhi effects like these (or other phonological processes) are usually the historical origin of morphosyntactically triggered mutation. For example, English fricative mutation (specifically, voicing) in words such as house [haus], plural houses [hauzɪz], and the verb to house [hauz] originates in an allophonic alternation of Old English, where a voiced fricative occurred between vowels (or before voiced consonants), and a voiceless one occurred initially or finally, and also when adjacent to voiceless consonants. Old English infinitives ended in -(i)an and plural nouns (of Class One nouns) ended in -as. Thus, hūs 'a house' had [s], and hūsian 'house (verb)' had [z]; however, the plural of hūs was hūs, being a neuter noun of the strong a-stem class. During the Middle English period, hous~hus, as part of the loss of gender and erosion of endings, developed plural variation, retaining hous [hu:s], the dative plural housen [hu:zən], which became extended to a general plural, and over time taking on the es plural from Old English Class 1 nouns, thus houses [hu:zəz]. After most endings were lost in English, and the contrast between voiced and voiceless fricatives partly phonemicized (largely due to the influx of French loanwords), the alternation was morphologized.



See also: Consonant voicing and devoicing § English

In Old English, velar stops were palatalized in certain cases but not others. That resulted in some alternations, many of which have been levelled, but traces occur in some word doublets such as ditch /dɪ/ and dike /daɪk/.

In the past tense of certain verbs, English also retains traces of several ancient sound developments such as *kt > *xt and *ŋx > *x; many of them have been further complicated by the loss of /x/ in Middle English.

The pair teach /tiːt͡ʃ/ : taught /tɔːt/ has a combination of both this and palatalization.

A second palatalization, called yod-coalescence, occurs in loanwords from Latin. One subtype affects the sibilant consonants: earlier /sj/ and /zj/ were palatalized, leading to an alternation between alveolar /s z/ and postalveolar ʒ/.

Another unproductive layer results from the Vulgar Latin palatalization of velar stops before front vowels. It is thus imported from the Romance languages, and /k ɡ/ alternate with /s dʒ/.

A combination of inherited and loaned alternation also occurs: an alternation pattern *t : *sj was brought over in Latinate loanwords, which in English was then turned into an alternation between /t/ and /ʃ/.

Celtic languages

Main articles: Breton mutations, Cornish grammar § Initial consonant mutation, Welsh morphology § Initial consonant mutation, Irish initial mutations, Manx language § Initial consonant mutations, and Scottish Gaelic phonology § Lenition and spelling

The Celtic languages are well-known for their initial consonant mutations.[1][2] The individual languages vary on the number of mutations available: Scottish Gaelic has one, Irish and Manx have two, Welsh, Cornish and Breton have four (if mixed mutations are counted). Cornish and Breton have so-called mixed mutations; a trigger causes one mutation to some sounds and another to other sounds. Welsh also has a mixed mutation (triggered by na, ni and oni). The languages vary on the environments for the mutations, but some generalizations can be made. Those languages all have feminine singular nouns mutated after the definite article, with adjectives mutated after feminine singular nouns. In most of the languages, the possessive determiners trigger various mutations. Here are some examples from Breton, Irish, Scottish Gaelic, and Welsh:

Breton Welsh Irish Scottish Gaelic Gloss
gwreg gwraig bean bean* woman/wife
bras mawr mór mòr big
ar wreg vras yr wraig fawr an bhean mhór a' bhean mhòr the big woman
kazh cath cat cat cat
e gazh ei gath a chat a chat his cat
he c'hazh ei chath a cat a cat her cat
o c'hazh eu cath a gcat an cat their cat

Older textbooks on Gaelic sometimes refer to the c → ch mutation as "aspiration", but it is not aspiration in the sense of the word used by modern phoneticians, and linguists prefer to speak of lenition here.

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 from the word once having the form *ak, and the final consonant influenced the following sounds.[3]


Welsh has three main classes of initial consonant mutation: soft mutation (Welsh: treiglad meddal); nasal mutation (Welsh: treiglad trwynol); and aspirate mutation, which is sometimes called spirant mutation (Welsh: treiglad llaes). The fourth category is mixed mutation, which calls for an aspirate mutation if possible but otherwise a soft mutation. The following tables show the range of Welsh mutations with examples. A blank cell indicates that no change occurs.

The mutation tsj corresponds to the td mutation and reflects a change heard in modern words borrowed from English. Borrowed words like tsips/jips (chips) can often be heard in Wales. Dw i'n mynd i gael tsips 'I'm going to get (some) chips'; Mae gen i jips 'I have chips'. However, the tsj mutation is not usually included the classic list of Welsh mutations and is rarely taught in formal classes. Nevertheless, it is a part of the colloquial language and is used by native speakers.


h-prothesis is a phenomenon in Welsh in which a vowel-initial word becomes h-initial. It occurs after the possessive pronouns ei 'her', ein 'our', and eu 'their': oedran 'age', ei hoedran 'her age' (c.f. ei oedran 'his age'). It also occurs with ugain 'twenty' after ar 'on' in the traditional counting system: un ar hugain 'twenty-one', literally "one on twenty".


Irish has two consonant mutations: lenition (Irish: séimhiú [ˈʃeː.vʲuː]) and eclipsis (Irish: urú [ˈʊ.ɾˠuː]).


Lenition (séimhiú) is indicated by an h following the consonant in question or, in some older typefaces and texts, by a dot (◌̇) above the letter that has undergone lenition. The effects of lenition are as follows:

  1. A stop becomes a fricative. Voicing is retained, as is place of articulation except for the coronals.
    • /pˠ//fˠ/
    • /pʲ//fʲ/
    • /t̪ˠ//h/
    • /tʲ//h/
    • /k//x/
    • /c//ç/
    • /bˠ//w/, /v/
    • /bʲ//vʲ/
    • /d̪ˠ//ɣ/
    • /dʲ//j/
    • /ɡ//ɣ/
    • /ɟ//j/
  2. /mˠ/ becomes /w/ or /v/; /mʲ/ becomes /vʲ/.
  3. /sˠ/ and /ʃ/ become /h/, but /sˠp(ʲ)/, /sˠm(ʲ)/, /sˠt̪ˠ/, /ʃtʲ/, /sˠk/, and /ʃc/ do not mutate.
  4. /fˠ/ and /fʲ/ are deleted.
Normal Lenition (Séimhiú) Gloss
peann /pʲaːn̪ˠ/ pheann /fʲaːn̪ˠ/ "pen"
teach /tʲax/ theach /hax/ "house"
ceann /caːn̪ˠ/ cheann /çaːn̪ˠ/ "head"
bean /bʲan̪ˠ/ bhean /vʲan̪ˠ/ "woman"
droim /d̪ˠɾˠiːmʲ/ dhroim /ɣɾˠiːmʲ/ "back"
glúin /ɡɫ̪uːnʲ/ ghlúin /ɣɫ̪uːnʲ/ "knee"
máthair /mˠaːhəɾʲ/ mháthair /waːhəɾʲ/, /vaːhəɾʲ/ "mother"
súil /sˠuːlʲ/ shúil /huːlʲ/ "eye"
freagra /fʲɾʲaɡɾˠə/ fhreagra /ɾʲaɡɾˠə/ "answer"

The following tables show how eclipsis affects the start of words. Eclipsis is symbolised in the orthography by adding a letter, or occasionally two letters, to the start of the word. If the word is to be capitalised, the original first letter is capitalised, not the letter or letters added for eclipsis. An example is the "F" in Ireland's national anthem, Amhrán na bhFiann.

Sound change Normal Eclipsis Gloss Notes
/pˠ//bˠ/ práta /pˠɾˠaːt̪ˠə/ bpráta /bˠɾˠaːt̪ˠə/ "potato" A voiceless stop or /fˠ, fʲ/ is voiced.
/pʲ//bʲ/ peann /pʲaːn̪ˠ/ bpeann /bʲaːn̪ˠ/ "pen"
/t̪ˠ//d̪ˠ/ tráta /t̪ˠɾˠaːt̪ˠə/ dtráta /d̪ˠɾˠaːt̪ˠə/ "tomato"
/tʲ//dʲ/ teanga /tʲaŋɡə/ dteanga /dʲaŋɡə/ "tongue"
/k//ɡ/ cat /kat̪ˠ/ gcat /gat̪ˠ/ "cat"
/c//ɟ/ ceann /caːn̪ˠ/ gceann /ɟaːn̪ˠ/ "head"
/fˠ//w/, /v/ focal /fˠɔkəlˠ/ bhfocal /vˠɔkəlˠ/ "word"
/fʲ//vʲ/ freagra /fʲɾʲaɡɾˠə/ bhfreagra /vʲɾʲaɡɾˠə/ "answer"
/bˠ//mˠ/ bainne /bˠaːnʲə/ mbainne /mˠaːnʲə/ "milk" A voiced stop becomes a nasal.
/bʲ//mʲ/ bean /bʲan̪ˠ/ mbean /mʲan̪ˠ/ "woman"
/d̪ˠ//n̪ˠ/ droim /d̪ˠɾˠiːmʲ/ ndroim /n̪ˠɾˠiːmʲ/ "back"
/dʲ//nʲ/ dinnéar /dʲɪnʲeːɾˠ/ ndinnéar /nʲɪnʲeːɾˠ/ "dinner"
/ɡ//ŋ/ glúin /ɡɫ̪uːnʲ/ nglúin /ŋɫ̪uːnʲ/ "knee"
/ɟ//ɲ/ geata /ɟat̪ˠə/ ngeata /ɲat̪ˠə/ "gate"
/e//nʲe/ éan /eːn̪ˠ/ n-éan /nʲeːn̪ˠ/ "bird" A vowel receives a preceding /n̪ˠ/ or /nʲ/ (broad preceding a/o/u, slender preceding e/i).
/i//n̪ˠi/ oíche /iːhə/ n-oíche /n̪ˠiːhə/ "night"


In Russian, consonant mutation and alternations are a very common phenomenon during word formation, conjugation and in comparative adjectives.

The most common classes of mutations are the alternation between velar and postalveolar consonants:

Other common mutations are:


Modern Hebrew shows a limited set of mutation alternations, involving spirantization only.[4] The consonants affected may be stem-initial, stem-medial, or stem-final.

Radical Spirantized
p f
k x
b v
These alternations occur in verbs:
 • בוא ← תבוא /bo/ /taˈvo/ ("come" (imperative) → "you will come"),
 • שבר ← נשבר /ʃaˈvaʁ/ /niʃˈbaʁ/ ("broke" (transitive) → "broke" (intransitive),
 • כתב ← יכתוב /kaˈtav/ /jiχˈtov/ ("he wrote" → "he will write"),
 • זכר ← יזכור /zaˈχaʁ/ /jizˈkoʁ/ ("he remembered" → "he will remember"),
 • פנית ← לפנות /paˈnit/ /lifˈnot/ ("you (f.) turned" → "to turn"),
 • שפטת ← לשפוט /ʃaˈfatet/ /liʃˈpot/ ("you (f.) judged" → "to judge "),
or in nouns:
 • ערב ← ערביים /ˈeʁev/ /aʁˈbajim/ ("evening" → "twilight"),
 • מלך ← מלכה /ˈmeleχ/ /malˈka/ ("king" → "queen"),
 • אלף ← אלפית /ˈelef/ /alˈpit/ ("a thousand" → "a thousandth"),

However, in Modern Hebrew, stop and fricative variants of ב‎‏, כ‎ and פ‎ are sometimes distinct phonemes:

 • אִפֵּר – עִפֵר /iˈpeʁ//iˈfeʁ/ ("applied make up" – "tipped ash"),
 • פִּסְפֵּס – פִסְפֵס /pisˈpes//fisˈfes/ ("striped" – "missed"),
 • הִתְחַבֵּר – הִתְחַבֵר /hitχaˈbeʁ//hitχaˈveʁ/ ("connected" – "made friends (with)"),
 • הִשְׁתַּבֵּץ – הִשְׁתַּבֵץ /hiʃtaˈbets//hiʃtaˈvets/ ("got integrated" – "was shocked"),

For a more in depth discussion of this phenomenon, see Begadkefat.


Rendaku, meaning "sequential voicing," is a mutation of the initial consonant of a non-initial component in a Japanese compound word:

Uralic languages

Main article: Consonant gradation

Word-medial consonant mutation is found in several Uralic languages and has the traditional name of consonant gradation. It is pervasive, especially in the Samic and Finnic branches.


Main article: Finnish consonant gradation

Consonant gradation involves an alternation in consonants between a strong grade in some forms of a word and a weak grade in others. The consonants subject to graduation are the plosives (p, t, k) that are followed by a vowel and preceded by a vowel, a sonorant (m, n, l, r), or h. The strong grade usually appears in an open syllable or before a long vowel.

Strong Weak Example Notes
pp p pappi → papit; lamppu → lamput Long consonants become short.
tt t katto → katot; kortti → kortit
kk k pukki → pukit; pankki → pankit
p v tapa → tavat Lenition.
t d katu → kadut; lahti → lahdet
k pako → paot
v puku → puvut; kyky → kyvyt In the combinations -uku- and -yky-.
j jälki → jäljet; sulkea → suljin When followed by e or i and preceded by h, l or r.
mp mm kampa → kammat Assimilation.
nt nn lento → lennot
lt ll kielto → kiellot
rt rr parta → parrat
nk /ŋk/ ng /ŋː/ kenkä → kengät

The gradation of loanwords may include gradation of the plosives that are not native to Finnish:

Strong Weak Example
bb b lobbaan → lobata
gg g bloggaan → blogata


Burmese exhibits consonant mutation, involving voicing in many compound words.

The primary type of consonant mutation is that if two syllables are joined to form a compound word, the initial consonant of the second syllable becomes voiced. The shift occurs in these phones:


sʰé (ဆေး) + áɴ (ခန်း) > sʰé ɡáɴ ("medicine" + "room" → "clinic")

The second type of consonant mutation occurs when the phoneme /dʑ/ after the nasalized final /ɴ/ becomes a /j/ sound in compound words.


"blouse" (အင်္ကျီ angkyi) can be pronounced /èɪɴí/ or /èɪɴjí/.

The third type of consonant mutation occurs when phonemes /p, pʰ, b, t, tʰ, d/, after the nasalized final /ɴ/, become /m/ in compound words:

tàɪɴ (တိုင်) + pɪ̀ɴ (ပင်) > tàɪɴ mɪ̀ɴ (တိုင်ပင်) ("to consult")
táʊɴ (တောင်း) + pàɴ (ပန်) > táʊɴ màɴ ("to apologize")
jɪ̀ɴ (လေယာဉ်) + pjàɴ (ပျံ) > lèɪɴ mjàɴ ("airplane")

Southern Oceanic languages

Mutation of the initial consonant of verbs is a feature of several languages in the Southern Oceanic branch of the Austronesian language family.

Central Vanuatu

Initial consonant mutation occurs in many Central Vanuatu languages like Raga:

nan vano "I went"
nam bano "I go"

Those patterns of mutations probably arose when a nasal prefix, indicating the realis mood, became combined with the verb's initial consonant.[5] The possible ancestral pattern of mutation and its descendants in some modern Central Vanuatu languages are shown below:

Proto-Central Vanuatu *k > *ŋk *r > *nr *p > *mp
Raga (Pentecost) x > ŋg t > d v / vw > b / bw
Northern Apma (Pentecost) k > ŋg t > d v / w > b / bw
Southern Apma (Pentecost) v / w > b / bw
Ske (Pentecost) z > d v / vw > b / bw
Lonwolwol (Ambrym) r > rV ∅ > bV
Southeast Ambrym x / h / ∅ > g t > d v / h > b
Northern Paama ∅ > k t > r
Central/Southern Paama k / ∅ > g / ŋ t / r > d
Nāti (Malekula) k / ʔ > ŋk t / r > nt / ntr v / w > mp / mpw
Maii (Epi) t > d v > b
Lewo (Epi) v / w > p / pw
Lamenu (Epi) ∅ > p
Bierebo (Epi) k > ŋk t / c > nd / nj v / w > p / pw
Baki (Epi) c > s v > mb
Bieria (Epi) t > nd v > mb
Nakanamanga (Efaté-Shepherds) k > ŋ r > t v / w > p / pw
Namakir (Shepherds) k > ŋ t / r > d v / w > b

New Caledonia

Initial consonant mutation also serves a grammatical purpose in some New Caledonian languages. For example, Iaai uses initial consonant mutation in verbs to distinguish between specific/definite objects and generic/indefinite objects:

Mutation Determinate object Indeterminate object Meaning
k > x kap xəp "welcome"
l > hl lele hlihli "pull, haul in"
n > hn nəŋ hnəŋ "brandish"
ɳ > hɳ ɳooc hɳuuk "tie"
t > θ təəʈ θəəʈ "lift up by the end"
w > hw wia hwiəə "turn, change"
v > hv vɛɖen hvɛɛʈ "carry on the shoulder"

Those forms likely derive from an earlier reduplication of the first syllable in which the interconsonantal vowel was deleted, resulting in a spirantization of the formerly reduplicated consonant.[6]


The Dholuo language (one of the Luo languages) shows alternations between voiced and voiceless states of the final consonant of a noun stem.[7] In the construct state (the form that means 'hill of', 'stick of', etc.) the voicing of the final consonant is switched from the absolute state. (There are also often vowel alternations that are independent of consonant mutation.)


Consonant mutation is a prominent feature of the Fula language. The Gombe dialect spoken in Nigeria, for example, shows mutation triggered by declension class.[8] The mutation grades are fortition and prenasalization:

Radical Fortition Prenasalization
f p p
s ʃ ʃ
h k k
w b mb
r d nd
j , ɡ ɲdʒ, ŋɡ
ɣ ɡ ŋɡ

For example, the stems rim- 'free man' and [ɣim-] 'person' have the following forms:

Indonesian and Malay

The active form of a multisyllabic verb with an initial stop consonant or fricative consonant is formed by prefixing the verb stem with meN- in which N stands for a nasal sharing the same place of articulation as the initial consonant:

An initial consonant that is an unvoiced stop or s is deleted, leaving only the nasal in its place.

Applied to verbs starting with a vowel, the nasal is realized as ng ([ŋ]).

Monosyllabic verbs add an epenthetic vowel before prefixing and produce the prefix menge-:

Verbs starting with a nasal or approximant consonant do not add any mutant nasal, only me-.[9]

The colloquial language drops me- prefix but tends to replace it with nasalization:[citation needed]


More information is available in the Latvian Wikipedia.

Mutation Example
b→bj gulbis→gulbja
c→č lācis→lāča
d→ž briedis→brieža
dz→dž dadzis→dadža
g→dz lūgt→lūdzu
k→c liekt→liecu
l→ļ sīlis→sīļa
m→mj zeme→zemju
n→ņ zirnis→zirņa
p→pj krupis→krupja
r→r teteris→tetera
s→š lasis→laša
t→š vācietis→vācieša
v→vj cirvis→cirvja
z→ž vēzis→vēža

Also two consonants can mutate as a group.

Mutation Example
kst→kš pāksts→pākšu
ln→ļņ cilnis→ciļņa
sl→šļ kāpslis→kāpšļa
sn→šņ atkusnis→atkušņa
zl→žļ zizlis→zižļa
zn→žņ zvaigzne→zvaigžņu


In Ute, also called Southern Paiute, there are three consonant mutations, which are triggered by different word-stems,[10] The mutations are spirantization, gemination, and prenasalization:

Radical Spirantization Gemination Prenasalization
p v pp mp
t r tt nt
k ɣ kk ŋk
ɣʷ kkʷ ŋkʷ
ts   tts nts
s   ss  
m ŋkʷ mm mm
n   nn nn

For example, the absolutive suffix -pi appears in different forms, according to the noun stem to which it is suffixed:

See also


  1. ^ Ball, M. J.; N. Müller (1992). Mutation in Welsh. London: Routledge. ISBN 0-415-03165-6.
  2. ^ Fife, James; Gareth King (1998). "Celtic (Indo-European)". In Andrew Spencer; Arnold M. Zwicky (eds.). The Handbook of Morphology. Oxford: Blackwell. pp. 477–99. ISBN 0-631-22694-X.
  3. ^ Ternes, Elmar. 1986. A Grammatical hierarchy of joining. In: Andersen, Henning. Sandhi phenomena in the languages of Europe. P.17-18
  4. ^ Glinert, Lewis (1989). The Grammar of Modern Hebrew. Cambridge: Cambridge University Press.
  5. ^ Crowley T, 1991. Parallel Development and Shared Innovation: Some Developments in Central Vanuatu Inflectional Morphology. Oceanic Linguistics, Vol. 30, No. 2, pp. 179-222
  6. ^ Lynch, John (2015). "The Phonological History of Iaai". Journal of the Linguistic Society of Papua New Guinea. 33. ISSN 0023-1959.
  7. ^ Stafford, R. (1967). The Luo language. Nairobi: Longmans.
  8. ^ Arnott, D. W. (1970). The Nominal and Verbal Systems of Fula. Oxford: Oxford University Press.
  9. ^ Examples adapted from Wikibooks:Indonesian prefix me
  10. ^ Sapir, Edward (1930). "The Southern Paiute Language (Part I): Southern Paiute, a Shoshonean Language". Proceedings of the American Academy of Arts and Sciences. 65 (1): 1–296. doi:10.2307/20026309. JSTOR 20026309.

Further reading