What is Adequate Cause?

Legal Definition
In criminal law. Adequate cause for the passion which reduces a homicide committed under its influence from the grade of murder to manslaughter, means such cause as would commonly produce a degree of anger, rage, resentment, or terror, in a person of ordinary temper, sufficient to render the mind incapable of cool reflection. Insulting words or gestures, or an assault and battery so slight as to show no intention to inflict pnin or injury, or an injury to property unaccompanied by violence are not adequate causes. Gardner v. State, 40 Tex. Or. R. 19, 48 S. W. 170; Williams v. State, 7 Tex. App. 396; Boyett v. State, 2 Tex. App. 100.
-- Black's Law Dictionary