an instance of invading a country or region with an armed force:Napoleon’s disastrous invasion of Russia in 1812 [mass noun]:in 1546 England had to be defended from invasion
an incursion by a large number of people or things into a place or sphere of activity:there was a brief pitch invasion when Sunderland scored
an unwelcome intrusion into another’s domain:random drug testing of employees is an unwarranted invasion of privacy