The noun "concentration" refers to the act, process, or ability of focusing one's attention on a specific object, as well as the act or process of reducing the volume of a liquid and removing the impurities from ore.

A field or course of study on which one focuses, especially as a student in a college or university.

A noun "concentration" represents the proportion of a substance in a whole, specifically referring to the amount of solute in a solution measured in suitable units.

The matching game pelmanism.