I'm from the United States, and I'm sure a lot of Americans might disagree with me, but.... I was raised to call the 3 daily meals: breakfast, dinner, and supper. The evening meal at home was always called "supper" regardless of whether it was a small meal or a large meal. If we had only a very small mid-day meal, (for example, just a sandwich) then it was called "lunch". A full mid-day meal was called "dinner".