Definition 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."
verb: penetrate or assault, in a harmful or injurious way
"The cancer had invaded her lungs."
verb: to intrude upon, infringe, encroach on, violate
"This new colleague invades my territory."
verb: occupy in large numbers or live on a host