"Yes, I had salad for dinner."
Translation:Do, ges i salad i ginio.
Ok, I've looked this up (sorry for the cranky post, must have been one of those days).... Lunch is specifically a midday meal and supper is specifically an evening meal, but dinner can be either, depending on which is the bigger meal. This is a largely cultural thing, since some people see one or the other as the 'main' meal of the day. In which case, both swper and cinio should be an acceptable of dinner, as both the midday and evening meal can be called as such. So I conclude that Lunch is Cinio, Supper is Swper and Dinner can be both!
I agree - this is a cultural thing. In North America, some places call the mid-day meal "dinner" and other places call it "lunch"; while some places call the evening meal "dinner" and others call it "supper." It's a bit confusing. I think, for questions like this, you'll have to accept both "cinio" and "swper" if you specify "dinner" in English. :-)
In the UK at least, supper also often refers to a very light meal or snack eaten late in the evening after the main evening meal (dinner/tea/whatever you want to call it). I'm not sure whether the Welsh swper covers this definition or not. Mealtime words in English are a minefield.