I already wrote about Irish noun genders here but what about nouns and adjectives when they come together? An adjective directly following a noun follows the gender rules relating to the noun. The same can be said for plural nouns and adjectives. Take a look at the two examples below using bróg which is a feminine noun.
| Bróga dearga | Red shoes |
| Tá na bróga dearga ar an urlár. | The red shoes are on the floor |
In the above examples, the adjective qualifies the noun, i.e. gives us more information about the noun. Therefore this is an example of an Attributive Adjective.
However, we must not forget other instances when nouns and adjectives come together. Let’s take a look at another example:
| Tá na bróga dearg | The shoes are red |
| Tá na cait dubh | The cats are black |
| Tá an gúna daor | The dress is expensive |
| Tá an léine mór | The shirt is big |
In this case, the adjective describes the state of the noun, rather than referring directly to the noun itself. And so, the noun is not qualified by the adjective. Instead, the adjective is used to provide information about the subject of the sentence. This is an example of a Predicative Adjective.
In these cases, it’s important to note that NO CHANGE is made to the adjectives that follow the noun, REGARDLESS OF THE GENDER of the noun, or whether the noun is singular or plural.
Remember, adjectives in Irish come after the noun, not before as happens in English.

A simple question (I hope)
I’m pretty sure that “the big rock” is “an charraig mhór”, but what about “a big rock”? Is it “carraig mór” or “carraig mhór”, and why?
many thanks
If I’m understanding correctly, this question is less about the lenition of carraig and more about mór? If so, adjectives undergo lenition after feminine nouns (carraig is a feminine noun), hence carraig mhór. This is regardless of whether they’re definite or indefinite.
perfect, thank you!