Walrus

Here's a two part question: what constitutes a liquid, and when does that liquid qualify as a soup?

A few days ago I ordered yogurt soup in hopes of a bowl of Yoplait. But, alas, it wasn't to be! My chagrin opened a passionate discussion (in my head) about the prerequisites involved in labeling soups, and liquids. There must be some, but I don't know them.

All I do know is I never again want to accidentally order something that induces vomiting. I paid for a bowl of ipecac.

(I would consider Yoplait yogurt a liquid, because it does flow, albeit very slowly. I'm perplexed.)