Wiktionary
n. The killing of a large number of people over a short period of time.
WordNet
Wikipedia
Mass murder (sometimes interchangeable with " mass destruction") is the act of murdering a number of people, typically simultaneously or over a relatively short period of time and in close geographic proximity. The FBI defines mass murder as murdering four or more persons during an event with no "cooling-off period" between the murders. A mass murder typically occurs in a single location where one or more people kill several others. Many acts of mass murder end with the perpetrator(s) dying by suicide or suicide by cop.
A mass murder may be committed by individuals or organizations whereas a spree killing is committed by one or two individuals. Mass murderers differ from spree killers, who kill at two or more locations with almost no time break between murders and are not defined by the number of victims, and serial killers, who may kill people over long periods of time. Mass murder is the hypernym of genocide, which requires additional criteria.
Mass murder is also defined as the intentional and indiscriminate murder of a large number of people by government agents; for example, shooting unarmed protesters, throwing grenades into prison cells, and randomly executing civilians. The largest mass killings in history have been governmental attempts to exterminate entire groups or communities of people, often on the basis of ethnicity or religion because of dislike or intolerance. Some of these mass murders have been found to be genocides and others to be crimes against humanity, but often such crimes have led to few or no convictions of any type.
Usage examples of "mass murder".
Right up to the point when you reached the safety of a base camp and did not initiate charges of mutiny, mass murder, arson, striking an officer, and so on.
I know that I briefly considered reporting this crime of mass murder.
If the Germans are committing mass murder under cover of war-and I think they are-President Roosevelt can Turn world opinion against them with this document.
Hitler, Stalin, Mao, Pol Pot, and others had sought power through intimidation and mass murder, wading to the throne through lakes of blood, and all of them had ultimately failed to achieve what silicon circuitry was in the process of bestowing upon Shaddack.
Am I committing mass murder if I prick my finger and lose a drop of blood?
General Asher pointed out that it was not the habit of the United States Army to sanction mass murder, and he was excoriated as a coward who refused to face up to facts.