We have already discussed some situations in which a treiglad meddal is used:
When feminine nouns follow the article 'y' (the) :
y bont the bridge pont noun (f)
When one or more adjectives follow a feminine noun:
dinas fawr fywiog large lively city
mawr adjective; bywiog adjective;
The pronouns dy, ei (masculine only) affect nouns which follow:
dy gôt your coat côt noun (f)
dy gar your car car noun (m)
ei lyfr his book llyfr noun (m)
Soft mutation occurs after the prepositions: am, ar, at, dan, dros, gan, heb, hyd, i, o, tan, trwy, wrth. For example:
Es i am dro trwy bentref heb weld neb.
I went for a walk through a village without seeing anyone.
tro walk; pentref village; gweld see;
We will now look at some other cases where a treiglad meddal is required.
Adjectives occurring before a noun cause a soft mutation of the noun:
hen dŷ old house tŷ noun (m)
hoff gerddoriaeth favourite music cerddoriaeth noun (f)
prif wlad main country gwlad noun (f)
The numbers un - one (feminine only) and dau/dwy - two - cause a soft mutation in a following noun, for example:
un ddafad, dwy ddafad, tair dafad dafad sheep (f)
one sheep, two sheep, three sheep
un llyfr, dau lyfr, tri llyfr llyfr book (m)
one book, two books, three books