Solutions are homogeneous mixtures of solute and solvent.

This definition says nothing about the physical state of a solution. While we commonly think of liquid solutions, solutions can just as easily be gases or solids.

• Solvent - the most abundant substance in a solution. In a liquid solution, the solvent does the dissolving.
   
• Solute - all other substances in a solution. In a liquid solution, the solute is dissolved.
   
  It is possible for a solution to have more than one solute, air and sea water are two examples, but a solution can have only one solvent.
   
• Solubility - The amount of solute that can be dissolved in a given amount of solvent at a given temperature. Different substances have different solubilities. There are even Rules for determining the solubility of salts.

A solution whose solvent is water is an aqueous solution.   A solution whose solvent is alcohol is a tincture.   Metallic solutions are alloys.