Welsh, like all modern Celtic languages, is characterized 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.
Welsh uses three mutations on consonants: the soft mutation (segment becomes voiced/lenites), the nasal mutation (segment becomes nasal), and the aspirate mutation (also called spirant mutation). Words beginning with a vowel are subject to h-prothesis under certain circumstances. Some sources consider h-prothesis of vowels to be a form of aspirate mutation, but since the environments of the two mutations are different, it is preferable to consider h-prothesis and aspiration two different mutations. In some circumstances mixed mutation is found, with aspirate mutation of c, p, t, and soft mutation of other mutable consonants.
The unmutated form, i.e. the “basic” form that dictionary entries are listed under, is known as the radical.
Mutations are generally not applied to personal names such as Bob or Gwen.
When under soft mutation, radical consonants lenite to voiced and/or fricative segments (/v ð/), as shown below:
| Radical | Soft mutation |
|---|---|
| c /k/ | g /ɡ/ |
| p /p/ | b /b/ |
| t /t/ | d /d/ |
| g /ɡ/ | ∅ (deleted) |
| b /b/ | f /v/ |
| d /d/ | dd /ð/ |
| m /m/ | f /v/ |
| (ll) /ɬ/ | (l) /l/ |
| (rh) /r̥/ | (r) /r/ |
| (ts) /t͡ʃ/ † | (j) /d͡ʒ/ |
In some situations c, p, t, g, b, d, m mutate but ll and rh do not. This partial soft mutation applies:
Other Welsh consonants such as ff or s or ch do not undergo mutation. A word which has already undergone mutation (such as beth (“what”) (short for pa beth (“what thing?”)) cannot be mutated a second time. Mutation is also not usually used in personal names such as Gwen or Dafydd. The g of recent English borrowings such as gêm (“game”) does not mutate.
The mutation of Welsh ts → j is only found in the colloquial language and not in the literary register. It is found only in loanwords from English, e.g. chips is rendered as tsips in Welsh and with the mutated form jips – for example, mae gen i jips.
In some situations the soft mutation only applies to feminine singular nouns, but not to masculine nouns or feminine plurals. These are:
In other circumstances (e.g. when an ordinary adjective such as hen (“old”) precedes a noun) the soft mutation applies to both masculine and feminine, and to both singular and plural.
Soft mutation occurs in a large number of different environments in Welsh. The following list is representative but not exhaustive.
In noun phrases and compound nouns such as "the girl", "old man", "two men", "small girl", "bookshop", it frequently happens that the second of two elements undergoes soft mutation.
The definite article y, yr, ’r triggers soft mutation of a feminine noun or adjective in the singular:
Masculine nouns and plural nouns of either gender do not mutate after the article:
In nouns, ll and rh never undergo soft mutation after the article, although they do in adjectives:
After the article, dau (“two”) mutates even when masculine:
The oblique-case relative pronoun y (“that”) followed by a verb does not cause mutation:
A feminine singular noun causes mutation in a following adjective or adjectives:
Exceptions:
Plural nouns (of either gender) and masculine nouns do not usually cause mutation except sometimes in titles such as the following:
There are many exceptions to this rule, e.g. Rhodri Mawr (“Rhodri the Great”)
When the second of two nouns describes or qualifies the first, there is mutation only if the first noun is feminine singular:
If the noun is masculine or plural, there is no mutation:
There is also no mutation in:
This rule is applied only sporadically in the case of proper names:
An adjective usually follows its noun in Welsh, but when the noun follows the adjective, both genders of the noun usually undergo soft mutation:
Superlative adjectives are an exception: they usually follow their noun; but if they precede, they do not usually cause mutation:
The second part of a compound noun where the first noun qualifies the second also usually has soft mutation in the second noun, even when the first noun is masculine:
But there is no soft mutation of ll and rh after n and r:
A pronoun + noun or noun + noun in apposition also has soft mutation of the second element:
The possessive adjectives (dy, ’th (“your (singular)”)) and (ei, ’i, ’w (“his/its”)) both trigger soft mutation:
This also applies when these words are used as object pronouns with a verb-noun:
But ei meaning "her" is followed by the aspirate mutation (see below):
When a full verb is used instead of a verb-noun, in a sentence starting with the particle fe or the relative pronoun a (“who, which”), the mutation disappears in both genders:
Feminine nouns are mutated after un (“one; same”), except for those starting with ll and rh:
But
But ll and rh are mutated in adjectives:
When un means “similar” it triggers soft mutation of both masculine and feminine nouns in the singular:
After the definite article y, yr, ’r, both genders of the word dau/dwy (“two”) are mutated, and the noun which follows is also mutated:
Other numbers are not affected by the article, nor do they usually cause mutation:
But occasionally saith (“seven”) and wyth (“eight”) cause soft mutation of c, p, t, ll, rh:
Also tri (“three (masculine)”) and chwe (“six”) trigger the aspirate mutation; and certain numbers trigger the nasal mutation when followed by blwyddyn (“year”) or diwrnod (“day”) (see below).
But numbers following a plural noun for literary effect are mutated:
The word cyntaf (“first”) usually follows its noun; but if it precedes, it does not cause mutation except in feminine nouns:
After ail (“second”), nouns of both genders are mutated:
After other ordinal numbers, only feminine nouns are mutated, and the first letter of the ordinal is itself mutated after the article:
But:
The predicate particle yn triggers soft mutation of a noun or adjective except with ll and rh:
The verb form sydd, sy triggers soft mutation of a predicate noun or adjective without using yn:
But the particle yn (which is thought to be a different word) before a verb-noun does not usually trigger mutation:
There is, however, mutation in a verb-noun if the object comes earlier in the clause, in sentences such as
The following prepositions cause mutation in a following noun:
The article blocks the mutation, unless the noun is feminine:
There is no mutation in i ti (“for you”), i mewn (“to inside”), i maes (“to outside”); but both i mi (“for me”) and i fi are used.
The word pam (“why”) (a compound of pa and am) also often triggers mutation:
The preposition yn (“in”) causes nasal mutation; â (“with”), gyda (“with”), tua (“towards”) cause aspirate mutation. Other prepositions, such as efo (“with”), wedi (“after”), ger (“near”), rhwng (“between”), ar gyfer (“for”) do not cause mutation at all.
In adjective phrases, as with noun phrases, the second element tends to have soft mutation:
There is no soft mutation of ll and rh after cyn (“as”), mor (“so”) and pur (“quite”):
Compound adjectives such as the following also have mutation in the second part:
Mutation occurs after the conjunctions neu (“or”) and ynteu (“whether”):
The first letter of verbs mutates after certain words:
In verbs expressing an opinion or belief used parenthetically, mi is omitted, but the mutation remains:
Similarly in colloquial language the question particle a is omitted, but the mutation remains:
Within compound verbs, such as reflexive and reciprocal verbs starting with ym-, there is mutation:
Soft mutation is found in various grammatical situations such as the following:
Adverbial phrases usually have soft mutation of the first letter:
Other adverbs are formed by adding yn before an adjective, which causes soft mutation (except ll and rh):
A noun or noun phrase used for addressing a person or people usually has mutation:
Any word directly following the subject (or virtual subject) in the same phrase usually undergoes mutation:
But ti (“you”) is unmutated in:
A word following an inflected verb or an imperative is also mutated, where the subject is contained in the verb ending and not expressed:
Mutation also occurs after dyma (“here is”), dyna (“there is”), dacw (“there is”):
But dyna pam (“that's why”) has no mutation.
An object or other word following a verb-noun is not mutated:
The reinforcing pronoun ti (“you”) becomes di after an imperative in sentences such as
Sentences such as the following, where a prepositional phrase or an adverb comes in the middle of a verb phrase, have mutation in the word which follows the inserted phrase:
Verbs or verb-nouns where an emphatic object precedes the verb often have mutation:
This also applies to an interrogative object:
Verbs or verb-nouns in a relative clause where the object pronoun is omitted similarly undergo mutation:
Either bod or fod may be used in indirect sentences such as the following, where bod or fod is followed by a noun (irrespective of the gender of the noun):
The choice is also possible in sentences such as the following:
When bod is followed by a subject pronoun, it changes in the same way as a noun with a possessive adjective, thus mod i, fod ti, fod e/o, bod hi, bod ni, bod chi, bod nhw (“that I/you/he/she/we/you (plural)/they”):
A voiceless stop becomes a voiceless nasal, while a voiced stop becomes a voiced nasal.
| Radical | Nasal mutation |
|---|---|
| p /p/ | mh /m̥/ |
| b /b/ | m /m/ |
| t /t/ | nh /n̥/ |
| d /d/ | n /n/ |
| c /k/ | ngh /ŋ̊/ |
| g /ɡ/ | ng /ŋ/ |
The other consonants and the vowels do not change under nasal mutation, although colloquially m and n are sometimes mutated, e.g. fy mham (“my mother”).
In most cases, only nouns (including verbal nouns) can undergo nasal mutation. The only exception is adjectives that are placed before the noun they modify:
But there is no mutation of the possessive adjective dy (“your”):
The possessive determiner fy (“my”) triggers nasal mutation:
Colloquially, fy may be reduced to ’y or deleted altogether (but still marked with an apostrophe); in both cases, the nasal mutation remains:
The preposition yn assimilates to ym before a bilabial consonant and to yng before a velar consonant.
Exception:
The words blynedd (“year”), blwydd (“years old”), and diwrnod (“day”) undergo nasal mutation after the numbers pum (“5”), saith (“7”), wyth (“8”), naw (“9”), deng (“10”), deuddeng (“12”), pymtheng (“15”), deunaw (“18”), ugain (“20”), can (“100”), and their compound forms.
Blynedd and blwydd also undergo nasal mutation after un (“one”) in composite numerals (i.e. where another number follows the noun to complete the meaning):
The negative prefix an- causes nasal mutation in words such as:
Under aspirate mutation, voiceless plosives become voiceless fricatives:
| Radical | Aspirate mutation |
|---|---|
| p /p/ | ph /f/ |
| t /t/ | th /θ/ |
| c /k/ | ch /χ/ |
The other consonants do not change under the aspirate mutation.
Vowel-initial words are sometimes said to undergo aspirate mutation by adding a prothetic h, but since the environments are different for vowels than for consonants, h-prothesis will be discussed separately below.
The possessive determiner ei/’i (“her”) (also i’w (“to her”)) triggers aspirate mutation:
The numerals tri (“three”) (masculine) and chwe (“six”) trigger aspirate mutation:
The adverb tra (“very”) triggers aspirate mutation:
Aspirate mutation is found after â (“with”) and its compounds tua (“towards”) and gyda (“with”):
But gyda fi (“with me”) can also have the soft mutation.
In some circumstances aspirate mutation is found with c, t, p, but soft mutation with other mutable consonants. (This is called "mixed mutation".)
Thus aspirate mutation occurs in:
but soft mutation in:
The particle ni may be omitted, but the aspirate mutation remains:
But na (equivalent to mai) meaning "that" followed by a focussed word does not cause mutation:
H-prothesis is the addition of h to a word starting with a vowel, including sometimes before i when it is pronounced /j/, but not when w is pronounced /w/.
The possessive determiners and infixed pronouns ’m (“my, me”), ei/’i (“her”) (also i’w (“to her”)), ein/’n (“our, us”), and eu/’u (“their, them”) trigger h-prothesis:
When ’i precedes a verb form as its direct object, it triggers h-prothesis even when it’s masculine singular:
The preposition ar (“on”) triggers h-prothesis of ugain (“twenty”) in complex numerals: