wildfire
US /ˈwaɪld.faɪr/
UK /ˈwaɪld.faɪr/

1.
a large, destructive fire that spreads quickly over woodland or brush
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The dry conditions led to a massive wildfire.
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Firefighters are working to contain the wildfire.
2.
a rapidly spreading and uncontrollable phenomenon or situation
:
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The news spread like wildfire across the internet.
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The new trend caught on like wildfire among teenagers.