What is a "hot meal"?

A hot meal is one that is prepared and cooked, as distinct from a sandwich, say, or some cheese with a piece of fruit.

In some countries, it has been the custom to set aside a couple of hours in the middle of the day for the mid-day meal, which allows the mid-day meal to be a full meal rather than something quickly prepared, requiring no cooking, that could be fit into a relatively brief "lunch hour".

P.S. For attestation that "hot meal" has the long-established meaning I've said it has and is not a mere "slang" term as @Kris alleges (see comment below, if @Kris has not already eaten it) see Meals in Science and Practice: Interdisciplinary Research and Business ... (H L Meiselman, ed.)

See also Food Cultures of the World Encyclopedia ( Ken Albala, ed).

In the term "hot meal", the part "hot" does not refer to temperature per se, but to the fact that the meal is prepared immediately prior to being served (usually involving cooking, but many other preparation techniques can be involved). If you left your packed lunch in a car parked in the sun, it might be hot by the time you get to eat it, but it still wouldn't be considered a hot meal. The quantitative aspect is covered by the "meal" part, as a meal is supposed to satiate for many hours; a quick bite that is cooked/fried might be called a hot snack instead.

As with many notions, the limits of what would be considered a "hot meal" are not sharp; I'm not sure whether accompanying sandwiches by a bowl of (hot) soup would turn lunch into a proper hot meal, though it is not completely cold either.