What is the name given to a liquid in which another substance can be dissolved?

The term used to describe a liquid in which another substance can be dissolved is "solvent." A solvent is typically a substance, often a liquid, that has the capability to dissolve a solute, resulting in a solution. For instance, in a saltwater solution, water acts as the solvent, while salt is the solute that dissolves in it. This interaction is fundamental in many biological processes, including those that occur within cells, where solvents facilitate the transport of nutrients and waste products.

The other terms provided do not accurately describe a liquid with dissolving capabilities. "Source" usually refers to a beginning point or origin of something, while "solvation" describes the process of surrounding solute particles with solvent molecules during dissolution. "Species" can denote a group of organisms or a category in biology but is unrelated to the concept of dissolution in a liquid context. Therefore, "solvent" is the correct term in this scenario.