›to make something less harmful, unpleasant, or bad: technologies that can mitigate global warmingmitigate damage/riskThe company was criticized for failing to mitigate risks at the plant.mitigate the effects/impact of sthThere isn't much more we can do to mitigate the negative effects of rising oil prices.
mitigating circumstances›LAWsituations 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.