concentration
noun
the strength of a solution; number of molecules of a substance in a given volume
the spatial property of being crowded together
Oppositesdistributionstrengthening the concentration (as of a solute in a mixture) by removing diluting material
Oppositesdilutionincrease in density
complete attention; intense mental effort
bringing together military forces
great and constant diligence and attention
Source: WordNet 3.1, Princeton University
