Here's why:

* Structure: Jelly has a defined shape. It doesn't flow like a liquid and will hold its form in a container.

* Rigidity: Jelly is rigid, meaning it resists deformation. You can cut it with a knife, and it doesn't immediately change shape like a liquid.

* Composition: Jelly is made up of a network of long, tangled molecules called polysaccharides (like pectin) suspended in water. This network gives the jelly its structure and rigidity.

It's important to note:

* Jelly can be quite *soft* and *flexible* compared to other solids.

* At high temperatures, it can melt and become more liquid-like. This is because the heat weakens the bonds holding the polysaccharide network together.

So, while jelly might feel a little squishy or jiggly, it's still a solid!