Irish initial mutations


, like all modern Celtic languages, is characterised by its initial consonant mutations. These mutations affect the initial consonant of a word under specific morphological and syntactic conditions. The mutations are an important tool in understanding the relationship between two words and can differentiate various meanings.
Irish, like Scottish Gaelic and Manx, features two initial consonant mutations: lenition and eclipsis .
Originally these mutations were phonologically governed by external sandhi effects: lenition was caused by a consonant being between two vowels, and eclipsis when a nasal preceded an obstruent, including at the beginning of a word.
Irish also features t-prothesis and h-prothesis, related phenomena which affect vowel-initial words.
See Irish phonology for a discussion of the symbols used on this page.

Historical development

Lenition

Lenition as an initial mutation originally stems from the historical allophonic lenition of an intervocalic consonant, both word internally and across word boundaries, i.e if a word ended in a vowel and the next word began with a consonant + a vowel, the consonant lenited.
Today, these former final vowels are usually elided, but the lenition of following consonants remains and has been grammaticised. For example, Proto-Celtic *esyo "his" caused the lenition of a following consonant due to its final vowel and its modern form a now causes lenition, keeping it distinct from a "her" and a "their", which cause h-prothesis and eclipsis respectively.
Lenition caused stops and *m to become fricatives, *s to debuccalise to, *f to elide, and the liquids *l, *n, *r to split into fortis and lenis variants. Though by the end of the Middle Irish period lenited *m largely lost its nasal quality, lenited *t debuccalised to, and lenited *d lost its coronal articulation.
Lenition did not only occur word initially, though non-initial lenition was never grammaticised. For example Proto-Celtic *knāmis → cnáim → cnáimh "bone", and *abalnā → aball → abhaill "apple tree".

Prothetic - and -

While it is not initially apparent, the prothesis of and stems from historical lenition combined with vowel reduction.
The prosthetic - of vowel initial words is a fossilised fragment of the Proto-Celtic masculine definite article *sindos. Before vowels, the *s of the ending *-os was lenited to, which devoiced the preceding *-d- to *-t.
  • i.e. *sindos → int → an t-).
The prosthetic of initial words is a fossilised fragment of the d of Proto-Celtic nominative feminine definite article *sindā and masculine genitive definite article *sindī. Since they ended in vowels, a following word initial *s was lenited to which devoiced the preceding *-d to *-t.
  • i.e. *sindā sūli → int ṡúil → an tsúil)
The prothetic of vowel initial words has two origins, the first being epenthetic to avoid vowel hiatus, and the second being the fossilised remnant of a historic consonant. For example, the *s of Proto-Celtic *esyās "her" was lenited between vowels to. Overtime *esyās was reduced to a but the remains when it is followed by a vowel initial word but is now written as part of the following word.

Eclipsis

Eclipsis originally stems from the historical coalescence of consonant clusters beginning with a nasal, both word internally and across word boundaries, i.e if a word ended in a nasal and the next word began with a stop or labial fricative, they would coalesce.
Today, many of the former final nasals have been elided, but still have an effect on the pronunciation of a following consonant, which has been grammaticised. For example, the Proto-Celtic genitive plural of the definite article *sindoisom has lost its final nasal and been reduced to na but it now causes the eclipsis of a following consonant or the prothesis of to a vowel.
The cluster reductions involved in eclipsis turned nasal stops followed by a voiced stop into nasal stops, nasal stops followed by a voiceless stop into voiced plosives, nasal stops followed by a voiceless labial fricative into a voiced fricative, and words which have lost their final nasal add an to vowel initial words.
These cluster reductions did not only occur word initially, though non-initial coalescence was never grammaticised. For example, Proto-Celtic *lindos → lind → linn "pool", and *kʷenkʷe → cóic → cúig "five".

Summary table

This table shows the orthographical and phonological effects of lenition, eclipsis, h-prothesis, and t-prothesis. Vowels are represented by and. Consonants are broad before and slender before. See also Irish orthography which has a table showing non-initial lenited consonants which elided or vocalised to form diphthongs or long vowels.
* Not all dialects contrast lenited and from their unlenited forms. See Irish Phonology#Fortis and lenis sonorants.

Environments of Lenition

After proclitics

After the definite article

The definite article triggers the lenition of:
  1. a feminine noun in the nominative singular
  2. : an bhean "the woman"
  3. a masculine noun in the genitive singular
  4. : an fhir "of the man" e.g. carr an fhir, the man's car
  5. a noun in the dative singular, when the article follows one of the prepositions de "from", do "to" or i "in"
  6. : do + an = don: don fhear "to the man"
  7. : de + an = den: den bhean "from the woman"
  8. : i + an = sa: sa chrann "in the tree"; san fhómhar "in the autumn"
Lenition is blocked when a coronal consonant is preceded by an.
Instead of leniting to, after the definite article, become :

After the vocative particle

  • a Bhríd "Bríd!"
  • a Sheáin "Seán!"
  • a chairde "my friends!"

    After possessive pronouns

The possessive pronouns that trigger lenition are mo "my", do "your ", a "his"
  • mo mhac "my son"
  • do theach "your house"
  • a pheann "his pen"

    After certain prepositions

  • de chrann "out of a tree"
  • faoi chrann "under a tree"
  • mar dhuine "as a person"
  • ó Chorcaigh "from Cork"
  • roimh mhaidin "before morning"
  • trí shioc agus shneachta "through frost and snow"
  • um Cháisc "at Easter"
  • idir fhir agus mhná "both men and women"
  • ar bhord "on a table"
  • do chrann "to a tree"
  • thar chrann "over a tree"

    After the preterite/conditional of the copula">Irish syntax#The copula is">copula

  • Ba dhuine mór é. "He was a big person."
  • Ba dheas uait é. "That was nice of you."

    After the preterite preverbal particles

  • Níor mhúinteoir é. "He was not a teacher."
  • Níor thug mé "I didn't give"
  • Ar shagart é? "Was he a priest?"
  • Ar tháinig sé? "Did he come?"

    After certain preverbal particles

  • ní thuigim "I don't understand"
  • má thagann sé "if he comes"
  • an fear a thabharfaidh dom é "the man who will give it to me"

    A verb in the preterite, imperfect or conditional

These were originally preceded by the particle do and often still are in Munster.
  • bhris mé "I broke"
  • bhrisinn "I used to break"
  • bhrisfinn "I would break"

    In modifier + head constructions

in these constructions if two coronals are adjacent.

After certain numbers

The singular form is used after numbers and is lenited in the following cases:
  • aon bhó amháin "one cow"
  • an chéad bhliain "the first year"
  • dhá theach "two houses"
  • beirt fhear "two men"
  • trí bhád "three boats"
  • ceithre bhó "four cows"
  • cúig phunt "five pounds"
  • sé mhí "six months"

    After preposed adjectives

Constructions of adjective + noun are written as compounds.
  • seanbhean "old woman"
  • drochdhuine "bad person"
  • dea-sheirbhís "good deed"
  • nuatheanga "modern language"
  • tréanmhuir "stormy sea"
  • fíorchneas "true skin"
  • ardbhrú "high pressure"
  • ógfhear "young man"

    After most prefixes

  • an-bheag "very small"
  • róbheag "too small"
  • aisghabháil "retake"
  • athbhliain "new year"
  • dobhréagnaithe "undeniable"
  • fochupán "saucer"
  • forbhríste "overalls"
  • idirchreidmheach "interconfessional"
  • ilphósadh "polygamy"
  • leasmháthair "stepmother"
  • míshásta "unhappy"
  • neamhchodladh "insomnia"
  • príomhchathair "capital city"
  • sobhriste "fragile"

    The second part of a compound

  • ainmfhocal "noun"
  • dúghorm "dark blue"
  • státfhiach "national debt"

    In head + modifier constructions

In these constructions coronals are lenited even following other
  • aimsir bháistí "rainy weather"
  • buidéil shú "bottles of juice"
  • teach Sheáin "Seán's house"

    Postposed adjectives in certain circumstances

  • bean dheas "a pretty woman"
  • na fir mhóra "the big men"
  • ainm an fhir bhig "the name of the small man"
  • sa chrann mhór "in the big tree"

    Environments of Eclipsis

After plural possessive pronouns

The possessive pronouns that trigger eclipsis are ár "our", bhur "your ", a "their"
  • ár gcairde "our friends"
  • bhur bpáistí "your children"
  • a mbád "their boat",
a can mean "his", "her" or "their", but these different uses can still be distinguished, since a causes lenition when used as "his", causes eclipsis when used as "their", and neither when used as "her".