From the Wikipedia : "Welsh, as with all other Celtic languages, often sees changes made to the beginning of words depending on the word that precedes it, or the role it plays in the sentence. These changes are known as "mutations", of which Welsh has three distinct types. Common situations in which a mutation may occur are when a word follows a preposition, possessive, or number."
The three types of mutation are:-
The three links will take you to further information (see below) about these commonly occurring mutations.
Most Welsh courses and teachers advise students not to worry too much about mutations at the outset. Fluent speakers will understand you if you forget to mutate a letter. With practice this will come naturally and there is perhaps, no need for beginning learners to make a conscious effort to apply these rules. It is important to remember, however, that mutations, "...pervade the entire structure of the language, and cannot be divorced from any aspect of it. These initial changes to words are as integral a part of Welsh as, say, the endings to words are in German or Russian." *
If you are determined to master the rules early on you could look out for the 'Mutant Alert' notice on the vocabulary pages and use these as an opportunity to refresh your knowledge by checking the links.
p t c b d g m ll rh
b d g f dd omit g f l r
mh nh ngh m n ng - - -
ph th ch - - - - - -
As you can see in the above table, there are nine consonants which undergo mutation in Welsh. There are three classes of mutations and different rules governing their use.
1. When the definite article ( y before a consonant or yr before a vowel) is used before a feminine noun the noun undergoes a soft mutation (this rule does not apply if it begins with ll- or rh- ).
When using the article before a masculine noun, soft mutation does not occur.
When using the article before a feminine noun, soft mutation occurs.
e.g. merch = girl ( n.f. ) Mae'r ferch wedi seiclo yma. - The girl has cycled here.
2. Adjectives which follow feminine nouns also undergo mutation.
e.g. tal = tall Mae'r ferch dal wedi seiclo yma. = The tall girl has cycled here.
3. Most Welsh prepositions require a soft mutation. See list below:
dros y penwythnos = over the weekend
dros benwythnos = over a weekend
4. The possessive pronouns 'your' (singular, familiar) = dy.....(di) and 'his' = ei...(e/o) require soft mutation.
llaw = hand
ei law...(e/o) = his hand
troed = foot
dy droed....(di) = his foot
Ei also means 'her', but when so used it requires an aspirate mutation. (see below)
5. Immediately after a command.
It should be noted that the above list is not exhaustive. There are more than 30 rules governing the use of soft mutations in Welsh. For a complete list go here:- Soft Mutation Rules ,,,
1. A nasal mutation occurs after use of the preposition yn (in). Yn does not cause mutation when used as a particle before a verb. Example:
If you were born in Cardiff (Caerdydd) and live in Portland (Portland) you might want to say:
"I was born in Cardiff but I live in Portland.'
This construction requires nasal mutation as follows (you will find help with pronunciation in the soundfile above):
' Cefais fy ngeni yng Nghaerdydd ond dwi'n byw ym Mhortland.'
2. A nasal mutation also occurs after fy . The word fy (my), causes nasal mutation in the words listed below:
dillad - clothes
brawd - brother
tadau - fathers
fy nillad - my clothes
fy nhadau - my fathers
Sometimes, in the spoken language, fy is omitted entirely.
1. After "a" a is the Welsh word for and ( ac is only used before vowels, hence it cannot cause an aspirate mutation).
ffiseg - physics
cemeg - chemistry
ffiseg a chemeg - physics and chemistry
radio - radio
teledu - television
radio a theledu - radio and television
2. The pronoun ei ( her ) causes aspirate mutation.
potel - ei photel
cinio - ei chinio
taith - ei thaith .
1. Ni , na and oni cause aspirate mutation of c, p and t and soft mutation of all other mutable consonants.
Pam na chymerwch bum munud i feddwl amdano?
Why not take five minutes to think about it?
* Gareth King: Modern Welsh A Comprehensive Grammar p. 13