mitigate
verb [ T ]
formal uk/ˈmɪtɪɡeɪt/ usto make something less harmful, unpleasant, or bad:
technologies that can mitigate global warming
mitigate damage/risk The company was criticized for failing to mitigate risks at the plant.
mitigate the effects/impact of sth There isn't much more we can do to mitigate the negative effects of rising oil prices.
mitigating circumstances
LAW
situations that are not an excuse for a crime, but that a court of law may consider to be important enough to reduce the blame or punishment of the accused person:
The judge said that there were no mitigating circumstances that would result in a lesser punishment.