My friend thinks cereal is soup. is it soup?

When you taking a shit and yo crap floats in da toilet water, that was food, that be floatin. Is that soup?

No, that’s why they are defined by two different words.

It is a soup. But since we have a name for foods that are served in milk ita called cold cereal.

proper soup is salty & savory so no

soup must be savory and contain meat and/or vegetables (or tomato cause tomato likes to break the rules)

A hamburger is beef. What's up with that?!?!

When soup cools, is it a cereal? How about sliced hotdogs in a bowl of milk?

Is a hotdog a sandwich?

Dry cereal > cereal with milk

Actually it isn't.

Simple. Soups are hot. Cereal is cold

It's not soup. Soup has to be salty and in most cases cooked to be called soup.

Even tho we have a Bulgarian soup that is made from water, yogurt, cucumber, garlic and dill. It's served cold, but it's still salty and has multiple ingredients. Similar to Greek tzatziki, but more liquidy...
This soup is not cooked, but still qualifies as a soup.

Cereal is just sweet nonsense you put in milk. One might argue it's another weird, cold soup, but one would have to be quite loony...

It's not soup; it's its own thing.

For something to be soup, it needs to have water as the base and needs to be cooked. Cereal meets neither of those. There are probably other reasons why it isn't soup, but those are the ones most obvious to me.

Soup must be cooked first. So, oatmeal is soup; cereal in general is not.

Technically cereal in a liquid could be characterised as soup, but no sane persone would say that.

That is not the definition of soup. Your friend is wrong.