Meaning & Definition of Invade in English

1. March aggressively into another's territory by military force for the purposes of conquest and occupation

• "Hitler invaded poland on september 1, 1939"

2. To intrude upon, infringe, encroach on, violate

• "This new colleague invades my territory"

• "The neighbors intrude on your privacy"

3. Occupy in large numbers or live on a host

• "The kudzu plant infests much of the south and is spreading to the north"

4. Penetrate or assault, in a harmful or injurious way

• "The cancer had invaded her lungs"