invade definition

1. march aggressively into another's territory by military force for the purposes of conquest and occupation
• examples: Hitler invaded Poland on September 1, 1939
2. occupy in large numbers or live on a host
• examples: the Kudzu plant infests much of the South and is spreading to the North
3. penetrate or assault, in a harmful or injurious way
• examples: The cancer had invaded her lungs