A 'think tank' is an institution, company or organisation who study or monitor a particular subject or area of expertise in order to provide information, solutions or advice. This is a noun used to describe a collection of people who are very knowledgeable about a particular subject and organise themselves around this. In a think-tank, you are paid to research your area of expertise full time in order to contribute to society. You are more likely to hear this used in professional contexts.

1. A think-tank of biologists and marine experts was formed to come up with some strategies to combat sea pollution.
2. A European think-tank on obesity has suggested more parks and outdoor gyms will help solve the problem.
3. A Middle Eastern think-thank will examine security in the area.

1. There are over 1,984 think-tanks in the US.
2. Human Rights Watch is a think-tank that publishes reports on violations of international human rights.