1. a sudden violent entry or invasion into a place
Usage: formal
2. a sudden increase in the population of animals in a particular area
Usage: biology; ecology

Examples

• The irruption of protesters into the building caught security off guard.
• There was a massive irruption of barbarian tribes across the Roman frontier.
• Scientists observed an irruption of snowy owls migrating south this winter.
• The irruption of locusts devastated crops across the region.
• An irruption of enemy forces through the mountain pass surprised the defenders.
• Bird watchers documented an unusual irruption of finches in the area.