To kill, killing or to have killed means to cause the death of a living organism.

The act of killing an animal, plant, or other life form can be said to have occurred when an outside force, usually another life form, has done something to cause it to die. This may be a result of several actions:

• a deliberate action such as war
• in the case of animals, slaughter; see slaughterhouse
• the result of a criminal act, the action or fault of another human being, see homicide and murder
• the results of an accident, such as a car crash. See negligent homicide
• an organism eating or otherwise ingesting another organism