invade, occupy -- (march aggressively into another's territory by military force for the purposes of conquest and occupation; "Hitler invaded Poland on September 1, 1939")
intrude on, invade, obtrude upon, encroach upon -- (to intrude upon, infringe, encroach on, violate; "This new colleague invades my territory"; "The neighbors intrude on your privacy")
invade, overrun, infest -- (occupy in large numbers or live on a host; "the Kudzu plant infests much of the South and is spreading to the North")
invade -- (penetrate or assault, in a harmful or injurious way; "The cancer had invaded her lungs")