- The definition of a meltdown is a situation where the fuel in a nuclear reactor overheats and causes the reactor core to melt, or a collapse of something.
- When a nuclear reactor overheats, this is an example of a meltdown.
- When the currency of a country starts to lose value and the economy starts to fall apart, this is an example of a meltdown.
- When the stock market tumbles 1,000 points in a day, this is an example of a meltdown.
- a situation in which a rapid rise in the power level of a nuclear reactor, as from a defect in the cooling system, results in the melting of the fuel rods and the release of dangerous radiation and may cause the core to sink into the earth
- a decline or breakdown in a situation or condition
- A severe overheating of a nuclear reactor core, resulting in melting of the core and escape of radiation.
- A disastrous situation; a failure or collapse: “No central bank or government institution existed &ellipsis; to halt the meltdown, to stop the sudden run on the banks” (Evan I. Schwartz).
- Informal An emotional breakdown.
- Severe overheating of the core of a nuclear reactor resulting in the core melting and radiation escaping.
- Four years have passed since the meltdown at the Chernobyl nuclear plant, but the grim legacy of the Soviet catastrophe is still unfolding. 
- A situation being likened to a nuclear meltdown; a crisis.
- Computer engineers were at a loss last night to explain why the Government had been hit by arguably the worst electronic meltdown in the history of Whitehall. 
- (figuratively) A tantrum.
meltdown - Computer Definition
The total cessation of operation of a computer system or network. A system meltdown can be caused by hardware or software. A network meltdown can be caused by hardware, software or excessive traffic.