military offensive in which large numbers of combatants of one geopolitical entity enter territory owned by another such entity
- Military: Getting troops to take control of enemy territory. Often a state invades another to start a war, but invasions can happen anytime during war. An invasion differs from a raid, in which the attacker does not intend to remain.
- Others: Sometimes, biologists speak about an invasive species. There might be locust swarms invading, or that some algae spread far more rapidly in new territory.