concentration

The direction of attention to a specific object.

The act, process or product of reducing the volume of a liquid, as by evaporation.

The act or process of removing the dress of ore and of reducing the valuable part to smaller compass, as by currents of air or water.

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

The proportion of a substance in a whole.

(chemistry) The amount of solute in a solution measured in suitable units (e.g., parts per million (ppm))

The matching game pelmanism.