Murder is the deliberate, malicious and unlawful killing of one human being by another. Sir Edward Coke defined it as: "when a man of sound memory, and of the age of discretion, unlawfully killeth within any county of the realm any reasonable creature in rerum natura under the king's peace, with malice aforethought, either expressed by the party or implied by law, so as the party wounded, or hurt, etc. die of the wound or hurt etc. within a year and a day after the same".
- "A man of sound memory, and of the age of discretion" means, in essence, a sane man.
- "reasonable creature in rerum natura" means any human being.
- "malice aforethought" is a legal concept and only requires a momentary intention immediately prior to the act.
- The common law rule that in order for an act to constitute murder, the victim must die within a year and a day of the wounding, has now been modified by statute in a number of jurisdictions.
In addition to various earthly prohibitions, the sixth of the Ten Commandments forbids murder. Note that soldiers in war are not generally considered to violate the sixth commandment, since war is lawful (in contradistinction to the definition of "murder", above.)
Murder is the unlawful killing of a human being with deliberate intent to kill: (1) murder in the first degree is characterized by premeditation; (2) murder in the second degree is characterized by a sudden and instantaneous intent to kill or to cause injury without caring whether the injury kills or not.
A group of crows is called "a murder of crows".