Here's why it's not simply a solid or liquid:

* Solid-like properties: Jelly has a definite shape and doesn't flow easily.

* Liquid-like properties: It's made up of water and can deform under pressure.

Colloids are mixtures where one substance is dispersed evenly throughout another. In jelly, the solid particles (pectin and sugar) are dispersed throughout the liquid (water). This gives jelly its unique properties.

You can think of it as a semi-solid, somewhere between a solid and a liquid.