The molarity of a substance is a scientific measurement of its concentration. Molarity describes the number of moles of a solute — a dissolved substance — per liter of liquid.
In chemistry, a mole is a standard unit of measurement for a chemical substance. The scientific term molarity describes the concentration of a substance, calculated as the number of moles divided by the total volume of the solution it's in. For example, a chemist might talk about the molarity of sodium chloride dissolved in water. Molarity comes from mole, which was coined by a German chemist from Molekül, German for "molecule."