1. (

• concentration ,

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

2. (

• concentration ,
• density ,
• denseness ,
• tightness ,
• compactness ,

) the spatial property of being crowded together ;

3. (

• concentration ,

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

4. (

• concentration

) increase in density ;

5. (

• concentration ,
• engrossment ,
• absorption ,
• immersion

) complete attention; intense mental effort ;

6. (

• concentration ,

) bringing together military forces ;

7. (

• assiduity ,
• assiduousness ,
• concentration ,

) great and constant diligence and attention ;