Meaning of invade

(verb) march aggressively into another's territory by military force for the purposes of conquest and occupation; "Hitler invaded Poland on September 1, 1939"

to intrude upon, infringe, encroach on, violate; "This new colleague invades my territory"; "The neighbors intrude on your privacy"

occupy in large numbers or live on a host; "the Kudzu plant infests much of the South and is spreading to the North"

penetrate or assault, in a harmful or injurious way; "The cancer had invaded her lungs"