For objects:
* Thickness: This is the most general and straightforward option.
* Density: This refers to the amount of matter packed into a given space.
* Bulk: This refers to the size and weight of an object.
* Sturdiness: This emphasizes the resistance to bending or breaking.
* Weight: Can be used if the object is heavy due to its thickness.
For liquids:
* Viscosity: This refers to a liquid's resistance to flow.
* Consistency: This describes the texture of the liquid.
For other contexts:
* Density: Can be used for things like forests or crowds.
* Concentration: Can be used for things like emotions or ideas.
The best noun to use will depend on what you want to emphasize.