- (countable & uncountable) A concentration is a large amount of something in one place or group.
- The oil-sands in Alberta, Canada, contain high concentrations of oil.
- The growing concentration of people in cities is causing new problems.
- (uncountable) Concentration is the ability to focus your attention on something.
- Runners mustn't worry or do anything else to break their concentration.
- A clean desk in a quiet place will help students improve concentration.
- The government's concentration should be on helping those in the greatest need.
- (chemistry) The amount of solute in a solution; the concentration of a solution is measured in parts per million (ppm)