Is jelly a liquid or a solid?

I am presuming here that you are British and are referring to a gelatin dessert although I think the same is true of the preserve that Americans call jelly and we call jam.
Jelly can hold its shape for a while, but it is a liquid because in time it will change its shape to that of its container (eventually free-standing jellies will collapse on the plate). It is a non-Newtonian fluid, which means that its viscosity (stickiness) varies depending on what force is applied to it.
This is as opposed to a Newtonian fluid such as tea which does not become harder to stir, the faster you stir it.

"Some examples of colloids are...milk (droplets of milkfat and protein suspended in water), and gelatin (protein suspended in water). In some mixtures, the molecules of the two substances are not completely mixed. Instead, the molecules of one substance gather into clumps that are dispersed through the other substance. These clumps are usually much larger than a single molecule, but small enough to remain suspended in the mixture. A mixture containing tiny clumps or particles that remain suspended within the mixture is called a colloidal dispersion, or colloid."

So, that doesn't say much about either solid or liquid...and I'm not sure it applies...but I just had to remember why colloid popped to mind.