meltdown

American  

[melt-doun] / ˈmɛltˌdaʊn /

noun

meltdowns plural

1. the melting of a significant portion of a nuclear-reactor core due to inadequate cooling of the fuel elements, a condition that could lead to the escape of radiation.

2. a quickly developing breakdown or collapse.

   a bond-market meltdown;

   the meltdown of a marriage.

3. Informal. a sudden loss of control over one’s feelings or behavior.

   My toddler had a meltdown when I tried to leave the house.

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meltdown British  

/ ˈmɛltˌdaʊn /

noun

1. (in a nuclear reactor) the melting of the fuel rods as a result of a defect in the cooling system, with the possible escape of radiation into the environment

2. informal a sudden disastrous failure with potential for widespread harm, as a stock-exchange crash

3. informal the process or state of irreversible breakdown or decline

   the community is slowly going into meltdown

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meltdown Scientific  

/ mĕlt′doun′ /

1. Severe overheating of a nuclear reactor core, resulting in melting of the core and escape of radiation.

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meltdown Cultural  

1. The most serious accident that can occur at a nuclear reactor. In a meltdown, the radioactive material in the reactor becomes very hot, melting some or all of the fuel in the reactor. A meltdown may or may not be followed by the release of radioactive material to the environment. A partial meltdown, with very little external radiation, occurred at Three Mile Island (see also Three Mile Island) in 1979; a complete meltdown happened at Chernobyl in 1986.

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Other Word Forms

Noun Inflected Forms

• meltdowns
  plural

Etymology

Origin of meltdown

First recorded in 1960–65; noun use of verb phrase melt down

Example Sentences

On the railways alone, he cited train delays, cancellations due to buckled rails, on-board air conditioning failure, cable and signalling meltdown.

From Barron's • Jun. 30, 2026

But in October 2008 at the height of the global economic turmoil fueled by America’s home mortgage meltdown, Greenspan appeared on Capitol Hill to a reception entirely different from the adulation he received while chairman.

From Los Angeles Times • Jun. 22, 2026

Where Alex previously had a "meltdown" during haircuts, he now enjoys them.

From BBC • Jun. 17, 2026

So while analysts expect some weakness following such a strong run-up this year, some believe worries of a continued meltdown appear to be misplaced.

From MarketWatch • Jun. 10, 2026

One morning toward the end of the school year, Mom had a complete meltdown.

From "The Glass Castle" by Jeannette Walls

Related Words

• accident
• adversity
• calamity
• casualty
• cataclysm
• crash
• debacle
• devastation
• disaster
• emergency
• failure
• fiasco
• hardship
• misery
• mishap
• tragedy
• trouble
• wreck