(1) The quantity of a particular substance (solid, liquid, or gas solute) that can dissolve in a particular solvent, yielding a saturated solution
(2) (botany) The tendency to separate readily into parts by spurious articulations
Solubility in general refers to the quality or property of being soluble or solvable. It is the ability of a substance (referred to as solute) dissolving in a solvent. The solute may be a solid, a liquid, or a gaseous substance. The solubility of the solute depends on its physical and chemical properties. Other factors affecting solubility are temperature, pressure, pH of the solution, and the properties of the solvent. Typically, the solvent is a liquid and water is one of the most common solvents used to dissolve solutes. There are solutes that readily dissolve in a solution while there are others that do not. Those that do not dissolve easily in a solution are called insoluble. A substance that is considered as insoluble is one in which there is less than 0.1 g per 100 mL of the solvent.1
Word origin: French solubilite, from Latin solubilis, solvere (loosen, dissolve)
1 Rogers, Elizabeth; Stovall, Iris (2000). “Fundamentals of Chemistry: Solubility”. Department of Chemistry. University of Wisconsin. Retrieved 22 April 2015.