Final answer:
The term for an accidental killing without intent during an unlawful act or improper performance of a lawful act is manslaughter. Manslaughter is different from murder, which requires intent to kill or premeditation. The legal distinctions carry significant implications for legal consequences.
Step-by-step explanation:
The term used for the killing of one accidentally, contrary to the intention of the parties, in the prosecution of some unlawful, but not felonious act, or in the improper performance of a lawful act, is manslaughter. This type of incident doesn't involve the intent to kill, which is a key factor that distinguishes manslaughter from murder. Manslaughter typically involves a level of negligence or recklessness, whereas murder requires premeditation or a willful act.
In legal contexts, the distinction between these terms is crucial, as they carry different legal implications and penalties. For example, Enmund v. Florida addresses the severity of the punishment in relation to the defendant's intention in a felony that leads to a murder.