noun. A bursting in; a breaking or rushing into a place; a sudden invasion or incursion.

noun. Synonyms Foray, raid.

noun. A bursting in; a sudden, violent rushing into a place.

noun. A sudden and violent inroad, or entrance of invaders.

noun. The action of irrupting or breaking into; a violent entry or invasion; an inbreaking; an intrusion.

noun. An abrupt increase of numbers of a particular animal.

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

noun. a sudden sharp increase in the relative numbers of a population

noun. a sudden violent entrance; a bursting in

"The white, two-foot-tall birds, which live in the Arctic the rest of the year, are known to fly south in large numbers every few winters in what is known as an irruption."

entering  entrance  entry  incoming  ingress  

incursion  inroad  inroads  inundation  irruptions  

air attack  air raid  air strike  blaze  boarding