I wrote lunch since to me mid-dag looks like mid-day, so I thought lunch. The translation told me supper....
The existential discussion on lunch/tea/dinner/supper occurs everywhere...between social classes in my home city; between one town and another; between lands and languages
Middag is the main meal of the day. Before the industrialization that meal was actually eaten at noon. However with the industrialization the meal moved to the early evening (just after the workday). The English word dinner has made the same transition from noon to the evening.
As the middag moved later so did the meal eaten during the first break of the day (around 8-9 before the industrialization), frukost. Around year 1900 the frukost changed meaning to breakfast (in Swedish and Norwegian, bot not Danish) and the English word lunch was borrowed as name for the meal that had been frukost before.
It is still common that middag is eaten in the middle of the days on weekends, and a smaller kvällsmat is eaten on the evenings. There is also supé (supper) for late meals.
In some provinces of Canada we say breakfast, lunch & supper. Others (mine) say breakfast dinner & supper. Personally, to avoid confusion over dinner being lunch or supper I use breakfast, lunch & supper. Canadian English is influenced by both American English & British English so there are variations leading to confusion.