1. An action undertaken in order to change what is happening or might happen in another’s affairs, especially in order to prevent something undesirable: Intervention was absolutely necessary when the two boys had a terrible fight on the playground.
2. The action of stepping in or interfering in any affair, so as to affect its course or issue: Intervention is frequently applied to the interference of a state or government in the domestic affairs or foreign relations of another country.
3. The fact of coming or being situated between in place, time, or order: The intervention of the fire caused a barrier between the city and the outskirts where Grace lived.
4. Economic action that is designed to counter a trend in a market: The intervention of the the central bank in the EU tried especially to stabilize a country’s currency.

A short-term intense therapy which emphasizes the identification of the circumstances that trigger an emotional trauma: "The emphasis is on neutralizing the trauma and mobilizing coping skills which will treat the crisis and make the situation as good as or better than the pre-crisis situation or condition."

A group trained in emergency medical treatment and in various methods for rendering psychiatric therapeutic assistance to a person or group of patients during a period of crisis; especially, instances involving suicide attempts or drug abuse.

The main objectives of such crisis assistance procedures are to help people cope with their current problems and to offer guidance and support for long-term therapies.