See more synonyms for meltdown on
  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.

Origin of meltdown

First recorded in 1960–65; noun use of verb phrase melt down Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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Contemporary Examples of meltdown

British Dictionary definitions for meltdown


  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 declinethe community is slowly going into meltdown
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for meltdown

by 1937 in the ice-cream industry; by 1956 in reference to a nuclear reactor, from verbal phrase, from melt (v.) + down (adv.). Metaphoric extension since 1979.

Online Etymology Dictionary, © 2010 Douglas Harper

meltdown in Science


  1. Severe overheating of a nuclear reactor core, resulting in melting of the core and escape of radiation.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

meltdown in Culture


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.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.