con·cen·tra·tion 
/ˌkɑ:nsənˈtreɪʃən/ noun
/ˌkɑ:nsənˈtreɪʃən/ noun 1 [noncount] : the ability to give your attention or thought to a single object or activity : the ability to concentrate
▪ the power of concentration ▪ All that noise is disturbing my concentration. ▪ The job required her full concentration. ▪ When you're tired it's easy to lose your concentration. 2 : the act of giving your attention to a single object or activity [singular] ▪ There was a concentration on ethics within the agency. ▪ His concentration [=focus] was on gathering evidence for the trial. [noncount] ▪ a student who chose law as his field/area of concentration [=his main area of study] 3 a : a large amount of something in one place [count] ▪ There is a concentration of wealth in the cities. [noncount] ▪ He objects to the concentration of power in the hands of a few rich men.
b [count] : a large number of people in one place
▪ Officials are expecting a heavy/high concentration of tourists [=are expecting many tourists] for the festival. 4 [count] : the amount of an ingredient in a mixture
▪ Contaminants were found in low concentrations. [=amounts] ▪ measuring the concentration of salt in a solution ▪ They detected high concentrations of pollutants in the water.
▪ the power of concentration ▪ All that noise is disturbing my concentration. ▪ The job required her full concentration. ▪ When you're tired it's easy to lose your concentration.
b [count] : a large number of people in one place
▪ Officials are expecting a heavy/high concentration of tourists [=are expecting many tourists] for the festival.
▪ Contaminants were found in low concentrations. [=amounts] ▪ measuring the concentration of salt in a solution ▪ They detected high concentrations of pollutants in the water.
