Uned Un - Adolygu

One of the essential features of the Welsh language is the manner in which the first letter of certain words mutates according to the circumstances in which it finds itself.  The term "mutation" refers to the substitution of an initial consonant in a word for another consonant, under various morphological or syntactic conditions.  In welsh, there are three sets of mutations: soft mutation, nasal mutation and aspirate mutations and each of these operate a different set of sound changes on certain consonants, where circumstances require.

 

See the mutation table for the various mutations.

Ansoddeiriau / adjectives
In welsh, most adjectives are placed after the noun.
Singular feminine nouns (fn) trigger a soft mutation in adjectives, e.g.
Merch (fn)  fach  (small girl)
Rhaglen (fn)  ddiddorol  (interesting programme)
Cath (fn)   ddel (pretty cat)
Gardd (fn)  bert (pretty garden)
Cadair (fn)  gyfforddus  (comfortable chair)
Coeden (fn)  fach (small tree)

There are exceptions to the rule, adjectives which precede the noun trigger a soft mutation, e.g.  hen (old),  hoff (favourite), prif (main), holl  (all) and ambell (occasional).
Hen  gar (old car)
Hoff ardd (favourite garden)
Prif lyfrgell   (main library)
Holl blant  (all children)

Ambell fachgen (occasional boy)

Y / YR / 'R
The underlying form of the definite article "the" is "y" in welsh, 
But this appears in three different forms depending on the words around it:

Y
When the following word begins with a consonant:
Y tŷ (the house), y car (the car), y siswrn (the scissors).

Yr
When the following word begins with a vowel or h-:
Yr arth (the bear), yr eliffant (the elephant), yr haf (the summer)

'r
When the preceding word ends with a vowel:
Chi'r, ni'r, mae'r.

Y / yr / 'r
Causes a soft mutation in singular feminine nouns. The exception to the rule are the letters "rh" a "ll".
y ferch (merch girl)
yr ardd (gardd garden)
y gadair (cadair chair)
y ddesg (desg desk)
y llwy (spoon) y rhaw (spade)

Prepositions often describe the relationship between persons or objects.
The following prepositions trigger a soft mutation:

Arddodiad (preposition)	Enghraifft / example
o (of, from)	o flaen (blaen) (in front of) o Gaerdydd (Caerdydd) (from Cardiff)
am (for, about)	am flynyddoedd (blynyddoedd) (for years)
dros (over)	dros bont (pont) (over a bridge)
ar (on)	ar blât (plât) (on a plate)
i (to)	i Landaf (to Llandaf)
at (to, towards)	at feddyg (meddyg) (to the doctor) at gymydog (cymydog) (to a neighbour)
dan (under)	dan bwysau (pwysau) ( under pressure)
drwy (through)	drwy ddamwain (damwain) (by accident)
gan  (with, by, from, since)	gan gyllell (cyllell) (with a knife)
heb (without)	heb gartref (cartref) (without a home)
wrth (by, to)	wrth orsaf (gorsaf) y trên (by the railway station) wrth wrando (gwrando) (by listening) bod yn garedig (caredig) wrth… (to be kind to…)

The verb usually comes first in a Welsh sentence. The present tense is formed by combining personal forms of "bod" = to be,  with the infinitive (or "verb-noun", as it is known in Welsh), e.g.

 

Bod	Subject	yn	Verb-noun
Mae	Rhys	yn	darllen
Rwy	i	yn	gyrru
Maen	nhw	yn	chwarae

 

Yn links the verb-noun to the subject. Yn darllen can be translated as reading,  yn gyrru as driving,  yn chwarae as playing.
After a vowel, yn is reduced to 'n.

Yn/'n NEVER comes before eisiau (want). This is the only exception. A verb-noun following eisiau does not need to be preceded by i ("to")

Mae	Rhodri	eisiau	car
Rwy	I	eisiau	mynd
Maen	nhw	eisiau	dod