From reading the many comments about “bríste" it is understood that there is a disjoint when it comes to standard English versus US English. There seem to be a couple of points. 1.) the problem with ‘trousers’ versus ‘pants’ and 2.) the confusion about nouns which are usually only used in a ‘plural’ form (search plurale tantum).
In my form (AUS/NZ/UK) of English, ‘trousers’ and ‘pants’ are somewhat interchangeable. However, ‘trousers’ are normally an outer garment worn by men. You can substitute the word ‘pants’ virtually everywhere that you use ‘trousers’. But not the other way around. ‘Underpants’ or the more feminine ‘panties’ could never be referred to as trousers. Trousers cover the full length of the leg. You can have ‘short pants’ i.e. ‘shorts’ - but you generally don’t have ‘short trousers’ in modern usage (maybe a construction already displaced due to adoption of the American ‘pants’ idiom?) The second problem is the use of words that are normally only used in the plural. I am sure both sides of the Atlantic (or Pacific) would say “I have a change of clothes in my bag” not “change of clothe”. Similarly, we all have tweezers, shears and scissors. We can have a ‘pair of scissors’ but not a ‘scissor’ (an ESL friend of mine told me she found my ‘scissor’ in her car after I had cleaned it. It took me a little while to understand what she was telling me) I can wear ‘trousers’ or I can wear ‘a pair of trousers’. I cannot wear ‘a trouser’. It is as nonsensical to refer to ‘a trouser’ as it is to refer to 'a scissor’. This is where there may be a slight difference between US English and non-US English. Maybe it is related only to clothing. It is now common here (AUS) to see advertisements for clothing, as in a brand-new advertisement (JUN2019) with letters referring to a photograph: - “J: Stretch Denim Jean”, “I: Bedford Trouser”, “L: Tech Jogger Pant”. They seem to have slipped up on the same page by adding the expected ‘s’ with “H: Straight Leg Denim Jeans”. To an earlier generation, ‘jean’, ‘pant’ and ‘trouser’ would be ludicrous. Presumably, to the current TV-raised generation these are as acceptable as substituting the US euphemism ‘bathroom’ for our own euphemism ‘toilet’! Can Americans really “Buy a new pant” or “Wear a jean to the mall”? I suspect not. But - there is a subtle difference in usage. I ended up on this page because I wrote to a ‘Type what you hear’ : - “Caitheann sí bríste.“ I was wrong and listening again proved that so. I had jumped to the conclusion that she was simply wearing trousers. But the narrator definitely said “brístí.“. This is plural. The translation given: - “She wears pairs of trousers” indicates that she was indeed clad in multiple pairs of that garment. There is an implication that she habitually wears multiple pairs of trousers. In English, if we wished to answer a question like “Does she wear skirts to school?” with a negative clarification, we could say: - “She wears trousers to school.” Here, the general “skirts” and “trousers” are plural. But to answer “Was she wearing a skirt?” We could answer “No, she was wearing a pair of trousers” or “No, she was wearing trousers”!! – but never “She was wearing trouser” or never “She was wearing a trouser” (for all English speakers, simply substitute the forms of “wear” with their equivalent forms of “carry” and substitute “scissors” for “trousers” and it is obvious.) I must also say that I haven’t reached the “continuous” tense forms in Irish yet. So we assume that Irish does indeed have distinct forms for the singular and plural names for lower body leg-enclosing garments. It is assumed further experience will clarify how they are used. I hope our “she” only wears multiple pairs of trousers as a grammatical illustration – much as that inconsiderate Paul is always drinking wine in front of the cat.
I totally agree. I've never heard anyone say She wears the pair of trousers. Or indeed He wears the pair of trousers. Nor have I heard anyone say She wears the pairs of trousers. This to me means that the one person is wearing more than one pair of trousers at the same time.
Caitheann is habitual, so she can wear a different pair of trousers every day, rather than all at the same time, just as "She wears dresses" doesn't imply that she wears them all at the same time.
So turn the phrase around - it's a phrase that is used to imply something about stereotypical gender roles in a household. If you were to use a word with an unambiguous singular/plural form, the equivalent sentence would probably be "He wears the dress" rather than "He wears the dresses".
Irish does have unambiguous singular and plural forms for bríste, they way you make that unambiguity clear in English is to use "pair of trousers" for the singular and "pairs of trousers" for the plural. It's irrelevant whether you would normally use that construction in your own spoken English, the point here is to indicate that you understand the difference between bríste and brístí.
Irish and English both differentiate between the simple present caitheann sí brístí/"she wears (multiple) trousers", and the continuous present/present progressive tá sí ag caitheamh brístí/"she is wearing (multiple) trousers".
They are different tenses, and mean different things, though not all languages make the distinction.