Because the noun ends with a slender consonant.

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Is fearr Gaeilg na Gaeltaċta ná Gaeilg ar biṫ eile
Agus is í Gaeilg Ġaoṫ Doḃair is binne

Thanks to you both for the answers. Sorry, one more question on this. I am trying to come up with an example of the plural of a noun ending with a broad consonant and can't ; can you - or anyone - give me an example of one and then add an adjective to it so that I can see it in action (ie. without lenition). Please and thanks.

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sceach = bush / thorn bush (ainmfhocal baininscneach den dara díochlaonadh, feminine noun of the second declension)

Nominative singular (ainmneach uatha): Chonaic mé sceach. = I saw a bush.
Nominative plural (ainmneach iolra): Chonaic siad na sceacha. = They saw the bushes.
Genitive singular (ginideach uatha): Tá mé os comhair na sceiche. = I am in front of the bush.
Genitive plural (ginideach iolra): Seo torthaí na sceach sin. = This is the fruit of those bushes.

Be gentle with me.....

Next word is: lá (day)

Bríd's daily thread would certainly make one of the answers very easy!
That has made me think: Give us this day, Bríd's daily thread instead of the usual prayer! Beginning to ramble so will stop typing now.....

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Just want to say, this is good practice! I've gotten very sloppy!

Redwolf

That's great. Not that you've got sloppy, of course! I was afraid the thread wouldn't get any response at all! It has confirmed to me what I always knew, that I know feck-all about some of the big stuff! And yes, 'feck' is a dialect thing and no caighdeán will change that.....

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More succinct

I can't think of any noun whose nominative plural forms ends with a broad consonant, and actually I think there's none
All plurals, in my opinion, ends with a vowel or with a slender consonant...

But there are many adjectives that wouldn't be lenited after a noun in the nominative plural, because all the nouns whose plural ends with a vowel don't lenite adjectives:

na mná móra (the tall women)
na cailíni deasa (the nice girls)
na daoiní cliste (the clever people)

etc

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Is fearr Gaeilg na Gaeltaċta ná Gaeilg ar biṫ eile
Agus is í Gaeilg Ġaoṫ Doḃair is binne

is maith liom an smaoineamh seo..... "lá" right?

Nominative singular (ainmneach uatha): Tá an lá go deas, nach bhfuil?
Nominative plural (ainmneach iolra): Réitím go maith leo na laethanta seo
Genitive singular (ginideach uatha): Glaofaidh mé ort i rith an lae
Genitive plural (ginideach iolra):

apologies, i copped out with the genitive plural, still havin trouble with it,

Next Word is: fál (fence)

No problem, what you have looks good.

For the Genitive plural (ginideach iolra), perhaps something like:

Beidh mé anseo go deireadh na laethanta saoire. "I will be here until the end of the holidays"

(Grammar check please. )

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Múinteoir Gaeilge - Irish Teacher
My "specialty" is Connemara Irish, particularly Cois Fhairrge dialect, but I can also speak Ulster and Munster Irish with native-level pronunciation.
Is fearr Gaeilge ḃriste ná Béarla cliste, cinnte, aċ i ḃfad níos fearr aríst í Gaeilge ḃinn ḃeo na nGaeltaċtaí.
Gaeilge Chonnacht (GC), go háraid Gaeilge Chois Fhairrge (GCF), Gaeilic Uladh (GU), Gaelainn na Mumhan (GM), agus Gaeilge an Chaighdeáin Oifigiúil (CO).

So wouldn't it be accurate to just say 'the plural adjective is lenited when the noun ends with a consonant and not lenited when the noun ends with a vowel'? That seems quite straightforward, even by my dodgy standards!

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