A "meltdown" refers to a severe failure in a system, often resulting in the release of harmful substances or energy. In the context of nuclear reactors, a meltdown occurs when the reactor core overheats, causing the nuclear fuel to melt. This can lead to the release of radioactive materials into the environment, posing significant health and safety risks. Meltdowns can also occur in other contexts, such as in electronics, where overheating can damage components. In psychology, a meltdown describes an intense emotional reaction, often seen in individuals with conditions like autism, where they may become overwhelmed and unable to cope with stressors.