"A wobbly tooth."
Some nouns form their plural by changing the last vowel or diphtong to something that ends in an i.
You may not have realized it but we do this in English - all words that form their plural by changing the last vowel or diphtong change it to something that ends in an e or an i.
man → men
foot → feet
mouse → mice (ignore silent e at the end!)
There are a few words that have a choice of plural, so we can use one (that is only similar to fiacaill by chance) to demonstrate how the adjective lenites depending on how the word pluralizes
Facal math – a good word
Faclan matha – good words
Facail mhatha – good words
Yes, but the confusion arises because people forget to say 'feminine singular noun' (here and on the Welsh course). So please, can all references to feminines causing lenition specify singular?
Rules for plural nouns are different, but people often get confused because of this omission. The confusion above, with this particular example, may also result from similarity with words that are masculine, or plural, or both, and some of which cause lenition, on top of the fact that fiacaill is sometimes spelt fiacal, so some might have thought that fiacaill was the plural, especially as there is no clue in this sentence that it is singular - if fiacaill were the plural, it would cause lenition. I was in fact only familiar with fiacal so I was confused.
fiacaill chugallach 'a wobbly tooth'
fiacal chugallach 'a wobbly tooth'
fiaclan cugallach 'wobbly teeth'
facal cugallach 'a wobbly word'
faclan cugallach 'wobbly words'
facail chugallach 'wobbly words'
and that's before you think about other cases.
There is no sure-fire way to recognise feminine nouns. The way children learn, even before they know what a feminine noun is, is to build a list in their heads of the words that fit the pattern. You can do the same. Every time you meet a word with a clue it's feminine, such as lenition of the adjective, lenition after the article, pronoun used, it gets added to your memory banks, and eventually the correct form comes out, without even thinking about the gender.
Well, there is a bit of confusion:
- I am only familiar with fiacal
- AFB only has fiacal and fiacaill
- Dwelly only has fiacaill
- Watson has facail(l) (not a well-respected dictionary)
- Duolingo has about a dozen questions with this word, always fiacaill
- Duolingo vocab list gives only fiacaill
- This appears to be a fairly new question
- Someone has the same query on another question, possibly even newer
Altogether this looks like a typo, so the next person who gets this as part of an exercise needs to flag it, so that a mod can either justify the spelling change or correct the typo on both questions.