In a full meltdown, such as the 1986 Chernobyl disaster in the Soviet Union, the rods melt completely and the release of energy causes an explosion that contaminates the surrounding area with radioactive material.

WSJ: Uranium Firms Take Hit After Earthquake

But if it worsens and you have a full core meltdown, that would certainly be catastrophic.

WSJ: Uranium Firms Take Hit After Earthquake

Jamie watched his colleague panic, which turned into a full-fledged meltdown.

CNN: How to avoid a major meltdown at work

That implies investors see the risk of a full-scale eurozone meltdown as having receded significantly.

BBC: Has Merkozy taken Italy out of the danger zone?

Finally, a strong middle class can only exist in an economy where everyone plays by the same rules, from Wall Street to Main Street. (Applause.) As infuriating as it was for all of us, we rescued our major banks from collapse, not only because a full-blown financial meltdown would have sent us into a second Depression, but because we need a strong, healthy financial sector in this country.

WHITEHOUSE: President Obama Speaks on the Economy

Large sun-grazing comets could bring on the sort of global electronics meltdown usually associated with electromagnetic pulse weapons or a full-scale nuclear exchange.

FORBES: Sun-Grazing Comets As Triggers For Electromagnetic Armageddon

Predications are hard, especially about the future, but it seems increasingly likely to me that the feedback loop may not stop, we will see a full-fledged bubble and that it will only be able to end in a meltdown.

FORBES: Housing's Positive Feedback Loop and the Coming Meltdown