melt‧down /ˈmeltdaʊn/ noun [uncountable and countable]

1. a very dangerous situation in which the material inside a nuclear reactor melts and burns through its container, allowing radioactivity to escape

2. a situation in which prices fall by a very large amount or an industry or economic situation becomes much weaker:
The stock market crash might lead to financial meltdown.

[TahlilGaran] Dictionary of Contemporary English ▲