Mutation of Initial Consonants in Middle Welsh

Three types of mutations are common in Middle Welsh:

  1. lenition (vocalic mutation): preceding element originally ended in a vowel.
  2. nasal: preceding element originally ended in -n.
  3. spirant: preceding element ended in -c, -s.

1.  Lenition

Consonant mutations are directly analogous to sound-changes within words; with the mutation known as lenition or softening the phrase is taken as a basic unit rather than the word.  It's a commonplace that many/most Indo-European languages tend to demonstrate a softening of single consonants in intervocalic positions (that is, between two vowels in a medial position).  Take a common word like 'kitchen.'  The Latin (coquina) shows the word with its hard (plosive) middle consonant; most of the Indo-European vernacular languages show some manner of softening of this same consonant, usually to a fricative or affricate: kitchen (English), cuisine (French), Küche (German), cocina (Spanish), cozinha (Portuguese).  The same softening takes place in Welsh (cegin), but with a significant difference: the same softening can occur at the beginning of a word when the preceding word ends in a vowel.  That is, for Welsh, the definition of 'intervocalic' is expanded so that it covers not only consonants in medial position, but also consonants in initial position.  This suggests that in early Welsh the phrase (article + noun, adjective + noun, etc.) was seen as a stronger unit that in other Indo-European languages.  So (as an example) nouns following an article or an adjective are lenited only when they are feminine; compare the Latin  endings -us (masc.), -a (fem.), -um (neut.) where only the feminine form ends in a vowel and would therefore place the initial consonant of the noun in an intervocalic position.              

        cegin < L. coquina

        niver < L. numerus

    in phrase - tud vawr < *tota mara (great people)

2. Nasal mutation

An initial consonant is nasalized by the presence of a nasal consonant (m or n) at the end of the preceding word.

    vy ghynghor < vyn cynghor 

    vym penn, vy mhenn < vyn penn 

    vyn nyvot < vyn dyvot 

    ym mwyt, y mwyt < yn bwyt

3.  Spirant mutation

An initial stop/plosive becomes a fricative when the preceding word ends in -c or -s.

The use of mutations in Middle Welsh is not always consistent, since mutations also spread analogically, by connection with grammatical functions: thus an adjective is mutated after a feminine singular noun, though not all feminine nouns end in a vowel. Mutations can also disappear analogically.

  1. Mutation is not consistently expressed in MW orthography; the presence of such pairs as 'y wlat' and 'y gwlat' do not necessarily indicate a difference in pronunciation.

    Table of Mutations
    Radical Lenition Nasal Spirant
    c corn gorn nghorn chorn
    t tat dat nhat that
    p prenn brenn mhrenn phrenn
    g gwr wr ngwr
    d dyn ddyn nyn
    b baryf varyf maryf
    ll llaw law
    rh rhan ran
    m mam vam


    1. the spirant 'dd' is normally written 'd', so the mutation is not always evident.
    2. 'rh' is generally written 'r', so the lenition is rarely distinguishable.
    3. 'll' and 'rh' are normally unlenited after -n, -r: yn llawen 'gladly'.

      I. Lenition occurs in the following situations:


      1. feminine singular after article:
        • y wreic (gwreic) 'the woman'
        • y gaer (caer) 'the fortress'
        • y vrenhines (brenhines) 'the queen'
        • (y llaw < OW ir lau, thus unlenited)
      2. genitive proper nouns after feminine singular noun (cf. Adj l):
        • Gulat Uorgant (Morgan) 'Morgan's kingdom'
        • enys Brydein (Prydein) 'the isle of Britain'
        • Branwen uerch Lyr (Llyr) 'Branwen daughter of Llyr'
        • also with adj. gen. of quality:
          llech uarmor (marmor) 'a slab of marble'
      3. genitive proper noun after dual (cf. Adj 2):
        • deu uab Uedravt (Medrawd) 'two sons of Medrawd'
        • also with adj. gen. of quality:
          y'r deu dafyn waet (gwaet) 'to the two drops of blood'
      4. in apposition to proper noun (titles, characteristics):
        • Arawn urenhin Annwuyn (brenhin) 'Arawn king of Annwuyn'
        • Llud vrenhin 'Llud the king'
        • Maxen wledig (gwledig) 'Maxen the ruler'
        includes mab, merch after personal names:
        • Branwen uerch Lyr (merch)
        • Math uab Mathonwy (mab) 'Math son of Mathonwy'
      5. proper noun in apposition to personal pronoun:
        • ef Uanawydan (Manawydan)
        • ynteu Wydyon (Gwydion)
        • ynteu Bwyll (Pwyli)
        • also: ni bechaduryeit (pechaduryeit) 'we sinners'
      6. after vocative particles a, ha, oia, och:
        • a vorwyn! (morwyn) '0 maiden'
        • oia wr! (gwr) 'ho, man'
        • och Ereint (Gereint) 'alas, Gereint'
        • also as vocative without particle at middle or end of sentence.
        • also after
          • llyma 'lo here'
          • llyna 'lo there'
          • nachef 'behold'
      7. used adverbially:
        • trigyaw y gyt a mi vlwydyn (blwydyn) 'to stay with me for a year'
          (except at beginning of sentence)
      8. used adjectivally in compounds:
        • kist vaen (maen) 'stone chest'
        • moruarch (march) 'sea-horse'
      9. after adjectives in compounds:
        • glasved (med) 'fresh mead'
        • amryuaelyon gerdeu (cerdeu) 'various songs'
        • prif lys (llys) 'chief court'
        • also occasionally after comparative and superlative.
      10. after some numerals:
        • un (1) - regularly with feminine
          • un wreic (gwreic) 'one woman'
          • un uerch (merch) 'one daughter'
          • occasionally with masc., meaning 'the same'
          • yn un uaes (maes) 'in the same field'
          • but yr un march 'the same horse'
        • deu/dwy (2) - regularly lenited
          • deu lu (llu) 'two hosts'
          • dwy uerchet (merch) 'two daughters'
          • but also deu cant '200', deu peth 'two things'
        • pump (5) - occasionally lenited by analogy
          • pump wraged (gwraged) 'five women'
          • but normally pump cantref 'five cantrefs'
        • chwech (6) - occasionally lenited by analogy
          • chwech wraged
          • but normally chwech blyned 'six years'
        • seith (7) - not usually lenited, though some examples
          • seith gantref (cantref)
          • but normally seith meibion 'seven boys'
        • wyth (8) - regularly lenited
          • wyth drawst (trawst) 'eight beams'
          • wyth gant (cant) '800'
          • but also wyth cant
        • naw (9) - occasionally lenited
          • naw rad (grad) 'nine ranks'
          • but normally naw cant '900'
        • mil (1000) - frequently lenited
          • mil vanyeri (banyeri) '1000 banners'
          • mil verthyr (merthyr) '1000 martyrs'
        A few numeral compounds are lenited as well:
        • pumwyr 'five men'
        • seithwyr 'seven men'
        • nawwyr 'nine men'
        • canwyr '100 men'
      11. after pronomials:
        • pa 'what'
          • pa le (lle) 'what place'
          • pa beth (peth) 'what thing'
        • pet 'how many'
          • pet wynt (gwynt) 'how many winds'
        • holl 'all'
          • holl gwn (cwn) 'all the dogs'
        • neill 'the one'
        • eil 'the other, second'
        • ryw 'some, such'
          • y ryw wr 'such a man'
        • amryw 'various'
        • kyfryw 'such'
        • sawl 'so, as many'
          • y saul geuri (ceuri) 'so many giants'
        • amyl 'many a'
        • ambell 'an occasional'
        • ychydic 'few, a little'
        • kwbyl 'complete'
          • cwbyl waradwyd (gwaradwyd) 'a complete insult'
      12. after prepositions:
        • a 'of'
        • am 'about'
          • am betheu 'about things'
        • ar 'on, in'
          • ar vrys (brys) 'in haste'
        • at 'to' - att Bwyll (Pwyll) 'to Pwyll'
        • dan 'under'
          • dan brenn (prenn) 'under a tree'
        • gan 'with'
          • gan bawb (pawb) 'with each'
        • heb 'without'
          • heb vwyt (bwyt) 'without food'
        • hyt 'as far as'
          • hyd galan Mei (calan) 'until the first of May
        • y 'to'
          • y vynyd (mynyd) 'upwards'
        • is 'below'
        • o 'of, from'
          • o gerd (cerd) 'of music'
        • tros 'over'
          • tros vor (mor) 'over the sea'
        • trwy 'through'
          • trwy lewenyd (llewenyd) 'through joy'
        • uch 'above'
          • uch benn (penn) 'above, overhead'
        • wrth 'at, by'
          • wrth Gynan 'with Cynan'
      13. after 2nd and 3rd singular masculine possessive pronoun:
        • dy davawt (tavawt) 'your tongue'
        • y benn 'his head'
        • y uryt (bryd) 'his mind'
        • o'y gyuoeth 'of his kingdom'
        although c, t, p often remain unlenited after th:
        • y'th castel 'in your castle'
        • a'th teulu 'with your retainers'
        • but usually y'th uedyant (medyant) 'in your power'
      14. after mor 'how' - mor druan (truan) 'how wretched'
      15. after neu 'or' - gwr neu wreic (gwreic) 'man or woman'
      16. after some verbal forms:
        1. as subject
          • after some forms of bot 'to be'
            • 3spi (oed, yssit)
            • 3s consuet. pres (bit, byd)
            • 3s imperf. (oed)
            • 3s consuet. pret. (bydei)
            • 3s pret. (bu)
            • 3s pres. subj. (bo)
            • 3s imperf. subj. (bei)
          • other verbs, only common with 3s imperf., 3s pluperf.
          • Subject is also normally lenited when it is separated from the verb:
            • y mae yno wr du (gwr) 'there's a black man there'
        2. as object:
          • normally lenited, especially when separated from verb.
          • some common exceptions:
            • after 3spi
            • after 3s pret.
            • after 3s pres. subj.
            • after impersonal passive constructions
        3. objects of destination after verbs of motion are lenited:
          • Gwyr a aeth Gatraeth (Catraeth) 'the men went to Catraeth'
        4. as nominal predicate (after most forms of bot):
          • ot wyt uorwyn (morwyn) 'if you are a maiden'
          • mi a vydaf gath (cath) 'I am a cat'
          • but occasionally bum ki 'I was a dog'
      17. after predicative particles yn, y:
        • yn vynych, (mynych 'frequent') 'often'
        • yn borth (porth) 'as a help'
        • yn wreic 'as a woman'
        • but note yn llawen, see above


      1. after feminine singular noun:
        • y wreic deccaf (teccaf) 'the fairest woman'
      2. after a dual noun:
        • deu uarch vawr (mawr) 'two big horses'
      3. after personal names (cf. Nouns 4)
        • Bran Uendigeit (bendigeit) 'Bran the Blessed'
        • Howel Uychan (bychan) 'Howel the small'
        • Beli Uawr (mawr) 'Beli the Great'
        • but also Beli Mawr, Ifor Bach
      4. comparative after noun in negative or interrogative sentence:
        • a dyvu o Vrython
          wr well no Chynon? (gwell)
          Did there come from the British
          a better man than Cynon?
      5. after: mor 'so, as'
        • mor uawr 'so big'
      6. kyn 'as'
        • kyn uawr 'as big'
      7. ry 'too'
        • ry uawr 'too big'
      8. after adjective or noun in compound:
        • canwelw (gwelw) 'pale white'
        • cad barawt (parawt) 'ready for battle'
      9. when adjective is used adverbially:
        • nyth elwir bellach byth yn vorwyn (pell) 'you will never more be called a maiden'
      10. predicatively after bot:
        • y bu barawt (parawt) 'it was ready'
        • nyt oed uwy (mwy) 'it was not more'
        • ny bydei vyw (bwy) 'he was not alive'
        • (there are many exceptions to this)
      11. after predicative and adverbial particles yn, y:
        • yn gyflum (cyflum) 'quickly'
        • yn barawt (parawt) 'ready'


      1. after adjective in compound:
        • ac a hir drigyawd ar hynny (trigyawd) 'and long remained upon them'
      2. after relative pronoun a:
        • yr erchwys a ladyssei y carw (liad) 'the pack which had killed the stag'
        after affirmative particle a:
        • a'r ulwydyn honno a dreulwys pawb o honunt hyt oet y wled (treulwys) 'and each of them spent that year until the time set for the feast'
        after interrogative particle a:
        • a uyd llawn dy got ti uyth? (byd) 'will your bag ever be full?'
      3. after negative particles ny, na:
        • ny allaf (gallu) 'I cannot'
        • na ovyn di (govyn) 'do not ask'
        after affirmative particles neu, ry:
        • ry geveis (caffael) 'I have got'
        after prefixes go-, dy-, di-, etc.
      4. after particle yt:
          yt gaffei (caffael) 'he should get'
      5. after interrogative particles
        • pa, py 'what, why'
          • py liw di? 'why do you colour?'
        • cwt 'where'
          • a wdosti cwd uyd nos yn arhos dyd? (byd) 'and do you know where the night waits for the day?'
      6. after conjunctions
        • pan 'when'
          • pan golles (colles) 'when he lost'
        • tra 'while'
          • tra vwyf (bwyf) 'while I am'
        • yny 'until'
          • yny welas (gwelas) 'until he saw'
      7. forms of bot after nominal predicate:
        • llawen uu y uorwen (bu) 'the maiden was glad'
        • dilesteir uyd dy hynt (byd) 'without hindrance will your journey be'


      1. often lenited as subject or object:
        • elwyf ui (mi) 'I might go'
      2. sometimes in apposition:
        • ni a awn, ui a thi (mi) 'we will go, you and me'
      3. after leniting words (cf. Nouns, Adjectives, passim):
        • gwae vi (mi) 'woe is me'
        • neu vinneu (minneu) 'or me'

      II. Spirant mutation occurs in the following situations;

      1. after 3rd singular feminine of pre- and infixed possessive pronouns:
        • y phenn (penn) 'her head'
        • y chlust (clust) 'her ear'
        • y throet (troet) 'her foot'
        • y'w phenn 'to her head'
      2. after numerals:
        • tri (3)
          • tri chantref (cantref) 'three cantrefs'
          • tri pheth (peth) 'three things'
        • chwech (6)
          • chwe thorth (torth) 'six loaves'
        • after preposition tra 'over'
          • tra thon (ton) 'over the wave'
          also when used as adverb 'very'
          • tra chas (cas) 'very hateful'
        • after conjunction and preposition ac, a:
          • a chledyf (cledyf) 'with a sword'
          • a thi (ti) 'with you'
          after conjunction no:
          • a dyvu o Vrython
            wr well no Chynon? (Cynon)
            'did there come from the British
            a better man than Chynon?'
          after conjunction na:
          • ny welynt neb ryw dim, na thy, nac aniuel, na mwc, na than, na dyn, na chyuanhed (ty, tan, cyuanhed) 'They could not see any kind of thing, neither house, nor beast, nor smoke, nor fire, nor man, nor dwelling.'
        • after negative particles ny, na (cf. Lenition, Verbs 3)
        • after affirmative particles neu, ry
        • after prefixes go-, di-, dy, etc.
        • after conjunction o:
          • o chigleu (cigleu) 'he has heard'
        • after cw, cwt:
          • cw threwna (trewna) 'where it settles'
          • cwd uyd (byd) 'where it shall be'
          • but also cwt gaffei (caffael) 'where he should get'

      III. Nasal mutation occurs in the following situations:

      1. after preposition yn:
        • ymhob (pob) 'in every'
        • yng Kymraeg (Kymraeg) 'in Wales'
        • yg charchar (carchar) 'in prison'
        • ymhoen (poen) 'in punishment'
      2. after prefixed pronoun fy (vyn):
        • vygkynghor (cynghor) /your counsel'
        • vynhat (tat) 'your father'
        • vymaraf (baraf) 'your beard'
        • vyggwreic (gwreic) 'your wife'
        • vymphen (penn) 'your head'
        • but also vy penn
      3. after some numerals, esp with nouns blyned 'year', diwarnawt 'day', dieu 'day', dyn 'man' and bu 'cow'.
        • seith (7)
        • naw (9)
        • dec (10)
        • deudec (12)
        • pymthec (15)
        • cant (100)
          • deng mlyned 'ten years'
          • dec nieu 'ten days'
          • deudec niwarnawt 'twelve days'
          • can mu 'a hundred cows'
        also by analogy with
        • pump (5)
        • wyth (8)
        • ugeint (20)
        • deugeint (40)
        and occasionally with
        • tri (3)
        • chwech (6)