concentration

(noun) the strength of a solution; number of molecules of a substance in a given volume.

(noun) the spatial property of being crowded together. Synonyms: density, denseness, tightness, compactness.

(noun) strengthening the concentration (as of a solute in a mixture) by removing diluting material.

(noun) increase in density.

(noun) complete attention; intense mental effort. Synonyms: engrossment, absorption, immersion.

(noun) bringing together military forces.

(noun) great and constant diligence and attention. Synonyms: assiduity, assiduousness.