British people don't universally call lunch "dinner"; rather, it's a regional and class-based linguistic quirk where "dinner" historically meant the main midday meal (now often called lunch), while the lighter evening meal was "tea" or "supper," with the terms shifting as work patterns changed due to the Industrial Revolution, but "dinner" remains for the big meal, even if eaten at midday (like Sunday dinner or school dinners) or in the evening.
"Dinner" used to be the main meal of the day, eaten around midday, because people got up very early and by then had worked like 6 hours. And they went to bed much earlier as a result.
The equivalent term in the United Kingdom is dinner lady. The role is also known as cafeteria lady, school caterer, lunchtime assistant, school meal supervisor, midday supervisor or kitchen assistant.
While it can also denote a light or late-evening snack either after or instead of the main meal, in the United Kingdom it is traditionally used to describe an informal main evening meal, as opposed to a dinner or a dinner party, which are a more formal meal with guests.
Linner is a late lunch or almost dinner meal. The name comes in reference to brunch, being a combination of the words "lunch" and "dinner" or "supper." Dunch comes in reference to brunch, being a combination of "dinner and "lunch." An alternate historical term is Russin.
The use of dinner or tea is often employed as a prime example of England's North-South division. The Oxford English Dictionary lists tea as “a light meal in the late afternoon, but locally in the U.K. (esp. northern), […] a cooked evening meal” (OED 2013), which suggests that tea is indeed a Northern form.
The answer lies in shifting dining traditions and how mealtime has evolved over the years. Eating the biggest meal of the day around noon started to become a thing of the past when more Americans began working away from their homes and farms.
If you normally only use the term "dinner" for rather more formal evening meals, and call your informal, family evening meal "supper" (pronounced "suppah"), you are probably upper-middle or upper class.
Historically, Southern cultures considered "dinner" as a noon meal and "supper" as an evening meal, particularly for farmers who needed a big meal to sustain them through the day. Modern usage varies by region and generation, with "dinner" being more commonly used for the evening meal today.
'Lunch Lady arms' is a slang term for having untoned arms that wiggle and jiggle as you use your arm (apparently they can also be called 'bingo wings' so thank you for that, Urban Dictionary).
