What is Extenuating Circumstances?

Legal Definition
Extenuating circumstances has different meanings in academia and law. In general it refers to circumstances that excuse somebody from a punishment they would receive under normal conditions.
-- Wikipedia
Legal Definition
Such as render a delict or crime less aggravated, heinous, or reprehensible than it would otherwise be, or tend to palliate or lessen its guilt Such circumstances may ordinarily be shown in order to reduce the punishment or damages.
-- Black's Law Dictionary
Legal Definition
Circumstances to be considered in mitigation of damages or punishment.
-- Ballentine's Law Dictionary