I think, in English at least, dinner is the main meal of the day, whereas supper is always the evening meal. For example someone may invite you for Sunday dinner, in which case the noon meal being the main meal of the day would be referred to as dinner. However in most other cases I would always think of dinner as being the evening meal, since it is usually the main meal of the day.
In Swedish, middag is the main meal of the day, and then there's kvällsmat in the evening if you eat a lighter meal at that point. (as I said this is the standard usage, so it's a simplified picture, but this is how most people use the words).
Most people eat middag after work, maybe an hour or two after coming home from work.
Take a look at the wiktionary article and open up the Inflection Table. I use wiktionary for most new words I come across - its a great resource!
It will tell you that stor & stort are for describing singular en & ett words, and stora is for describing plural and definite nouns. In this sentence, lunchen is definite.
Ett stort bord / A large table
En stor lunch / A big lunch
Den stora lunchen / The big lunch
De stora luncerna / The big lunches
(If I got something wrong please point it out).
We choose the large dinner is correct. I am neither posh nor from the South of the UK. So, breakfast, dinner, tea, maybe push the boat out, supper as well. As a 'gut' feeling, appropriate here, dinner is probably said by more people in the UK as a whole than poncy lunch. I have lived in England, Scotland and Wales. Dinner is more often used than lunch. If I wanted to be posh, I would say 'lunchen'. Also big dinner, is inelegant, so if you are going to up registers, then large dinner. Here ends the rant, I'm off for my brecky.
The problem with accepting "dinner" for lunch is that it will benefit a very small number of people, while accidentally teaching the wrong meaning to a vastle larger number of other people. However, whether it's posh or not, every native English speaker understands the meaning of "lunch". So it really is the least bad option.
Thank you for the reply. I don't agree. There are a significant number of speakers of an English who prefer dinner to lunch, and is understood for such. I take your point you may not wish to script for every possibility, din-dins...etc So let the dominance of the dialect of Southern Saxon continue. I was not asking you to use 'dinner' for lunch, but only that 'dinner' is accepted as a correct answer by those who use this term for the midday meal. Call it lunch/lunchen, but accept that 'dinner' is used by a significant number of people, friends in both Oz and New Zealand do use it too, let alone Ireland, where I also lived. I'm away for mi dinner. Tack bra