Murder

Murder is the unlawful killing of another human without justification or valid excuse committed with the necessary intention as defined by the law in a specific jurisdiction. This state of mind may, depending upon the jurisdiction, distinguish murder from other forms of unlawful homicide, such as manslaughter. Manslaughter is killing committed in the absence of malice, such as in the case of voluntary manslaughter brought about by reasonable provocation, or diminished capacity. Involuntary manslaughter, where it is recognized, is a killing that lacks all but the most attenuated guilty intent, recklessness.

Most societies consider murder to be an extremely serious crime, and thus believe that a person convicted of murder should receive harsh punishments for the purposes of retribution, deterrence, rehabilitation, or incapacitation. In most countries, a person convicted of murder generally receives a long-term prison sentence, a life sentence, or capital punishment. Some countries, states, and territories, including the United Kingdom and other countries with English-derived common law, mandate life imprisonment for murder, whether it is subdivided into first-degree murder or otherwise.

The modern English word "murder" descends from the Proto-Indo-European *mŕ̥-trom which meant "killing", a noun derived from *mer- "to die".

Proto-Germanic, in fact, had two nouns derived from this word, later merging into the modern English noun: *murþrą "death, killing, murder" (directly from Proto-Indo-European*mŕ̥-trom), whence Old English morðor "secret or unlawful killing of a person, murder; mortal sin, crime; punishment, torment, misery"; and *murþrijô "murderer; homicide" (from the verb *murþrijaną "to murder"), giving Old English myrþra "homicide, murder; murderer". There was a third word for "murder" in Proto-Germanic, continuing Proto-Indo-European *mr̥tós "dead" (compare Latin mors), giving Proto-Germanic *murþą "death, killing, murder" and Old English morþ "death, crime, murder" (compare German Mord).

The -d- first attested in Middle English mordre, mourdre, murder, murdre could have been influenced by Old French murdre, itself derived from the Germanic noun via Frankish *murþra (compare Old High German murdreo, murdiro), though the same sound development can be seen with burden (from burthen). The alternative murther (attested up to the 19th century) springs directly from the Old English forms. Middle English mordre is a verb from Anglo-Saxon myrðrian from Proto-Germanic *murþrijaną, or, according to the Oxford English Dictionary, from the noun.

The eighteenth-century English jurist William Blackstone (citing Edward Coke), in his Commentaries on the Laws of England set out the common law definition of murder, which by this definition occurs

when a person, of sound memory and discretion, unlawfully kills any reasonable creature in being and under the king's peace, with malice aforethought, either express or implied.

At common law, murder was normally punishable by death.