Since 1973 Amnesty International has adopted the simplest, broadest definition of torture:
"Torture is the systematic and deliberate infliction of acute pain by one person on another, or on a third person, in order to accomplish the purpose of the former against the will of the latter."
In 1986, the World Health Organization working group introduced the concept of organized violence, which was defined as:
"The inter-human infliction of significant, avoidable pain and suffering by an organized group according to a declared or implied strategy and/or system of ideas and attitudes. It comprises any violent action that is unacceptable by general human standards, and relates to the victims’ feelings. Organized violence includes “torture, cruel inhuman or degrading treatment or punishment” as in Article 5 of the United Nations Universal Declaration of Human Rights (1984). Imprisonment without trial, mock executions, hostage-taking, or any other form of violent deprivation of liberty, also fall under the heading of organized violence."
An even broader definition was used in the 1975 Declaration of Tokyo regarding the participation of medical professionals in acts of torture:
For the purpose of this Declaration, torture is defined as the deliberate, systematic or wanton infliction of physical or mental suffering by one or more persons acting alone or on the orders of any authority, to force another person to yield information, to make a confession, or for any other reason.
Source: Wikipedia on Torture: