There are various ways to express concentration, including:

* Molarity (M): Moles of solute per liter of solution.

* Molality (m): Moles of solute per kilogram of solvent.

* Mass percentage (%): Mass of solute per 100 grams of solution.

* Volume percentage (%): Volume of solute per 100 milliliters of solution.

* Parts per million (ppm): Mass of solute per million parts of solution.

The specific term used will depend on the context and the desired level of precision.