1. sudden violent entries or invasions into a place
2. sudden increases in animal populations, especially birds moving into new areas
Usage: ecology; ornithology

Examples

• The irruptions of barbarian tribes contributed to the fall of the Roman Empire.
• Military irruptions across the border created international tensions.
• Scientists studied the irruptions of snowy owls into southern regions.
• The irruptions of locusts devastated crops across the region.
• Bird watchers eagerly anticipated the winter irruptions of northern finches.
• Historical records document several irruptions of nomadic peoples into settled territories.