What is defined as the crime of killing a human being without malice aforethought?

The crime of killing a human being without malice aforethought is defined as manslaughter. This distinguishes manslaughter from other forms of homicide, which typically involve an intent or malice towards the victim. Manslaughter is often considered a lesser charge because it can happen in situations where the perpetrator may have acted in the heat of passion or under circumstances that do not involve premeditation or intent to kill.

Homicide is a broader term that encompasses all instances of one human killing another, including both lawful and unlawful acts, so it does not specifically define the lack of malice aforethought. Assault refers to the act of inflicting physical harm or threatening someone, which is different from killing. Negligence involves failure to take reasonable care to avoid causing injury or loss to another party, but it is not specifically a type of killing. Therefore, manslaughter accurately captures the essence of the crime described in the question.