In a political sense, conspiracy refers to a group of persons united in the goal of usurping or overthrowing an established political power. Typically, the final goal is to gain power through a revolutionary coup d'?tat or through assassination.
In criminal law, a conspiracy is an agreement between two or more persons to break the law at some time in the future.
A civil conspiracy or collusion is an agreement between two or more parties to deprive a third party of legal rights or deceive a third party to obtain an illegal objective.
A cabal is a group of people united in some close design together, usually to promote their private views and/or interests in a church, state, or other community, often by intrigue.
A conspiracy theory explains an event as being the result of an alleged plot by a covert group or organization or, more broadly, the idea that important political, social or economic events are the products of secret plots that are largely unknown to the general public.