concentration - noun

the strength of a solution; number of molecules of a substance in a given volume

the spatial property of being crowded together

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

increase in density

complete attention; intense mental effort

bringing together military forces

great and constant diligence and attention

concentration - thesaurus

absorption   assiduity   assiduousness   compactness   denseness   density   engrossment   immersion   tightness