A sudden or abrupt onset of something really bad is an outbreak. You could experience an outbreak of measles or an outbreak of violence; either way, try to protect yourself.

When you talk about an outbreak of something, it's almost always something terrible, or at least unwanted. You might hear about an outbreak of war in a distant country, or an outbreak of violence in a big city, or an outbreak of disease among farm animals. Outbreak started as a Middle English verb around 1300, becoming a noun meaning "eruption" about three hundred years later.

Definitions of outbreak

n a sudden violent spontaneous occurrence (usually of some undesirable condition)

“the outbreak of hostilities”
eruption, irruption
a widespread outbreak of an infectious disease; many people are infected at the same time
a return of something after a period of abatement
an epidemic that is geographically widespread; occurring throughout a region or even throughout the world
Type of:
happening, natural event, occurrence, occurrent
an event that happens

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