An invasion happens when one country or group of people enters another country's land, often with force. This can also describe any situation where something unwanted takes over.
Imagine if your friends decided to move into your backyard without asking - that would be an invasion! But the word "invaded" is used in many situations beyond just countries. For example, a new idea or a problem can invade your life and cause trouble. You might feel invaded by a lot of noise or mess at home. In these cases, something is taking over your space or attention in a way that's not welcome.
To move into.
Example: Under some circumstances police are allowed to invade a person's privacy.
