When you mitigate something, you make it less bad — less painful, less dangerous, or less serious. You do not wipe the problem out; you take some of the harm away. A doctor may mitigate pain with medicine. A city may plant trees to mitigate flooding. Companies talk about mitigating risk, meaning they add a plan so the worst result is less likely, or less damaging if it happens. News and school writing use it a lot for climate change: to mitigate climate change is to try to slow the harm. The word feels formal. In everyday talk people often say reduce, ease, or lessen. You mitigate a thing (pain, damage, effects, risk), not a person — though actually, older English could mean “calm someone down,” and you almost never hear that now.