This root comes from the Latin word "solvō," meaning "to loosen" or "to dissolve." You can see this root in words like:
* Solve: To find the answer to a problem.
* Solvent: A liquid that dissolves another substance.
* Resolvable: Capable of being solved.
* Dissolve: To become incorporated into a liquid.
So, the root "solv" in "solubility" refers to the ability of a substance to be dissolved or loosened in a solvent.