- a disastrous collapse or breakdown；an uncontrolled emotional outburst or a mental collapse
noun: meltdown, plural noun: meltdowns
- 1. a disastrous collapse or breakdown the global financial system suffered a major meltdown
- ▪ informal an uncontrolled emotional outburst or a mental collapse the story will revolve around her meltdown following the accident
- 2. an accident in a nuclear reactor in which the fuel overheats and melts the reactor core or shielding.