invade (Verb) — March aggressively into another's territory by military force for the purposes of conquest and occupation. ex. "Hitler invaded Poland on September 1, 1939"
invade (Verb) — To intrude upon, infringe, encroach on, violate. ex. "This new colleague invades my territory"
invade (Verb) — Occupy in large numbers or live on a host. ex. "the Kudzu plant invades much of the South and is spreading to the North"
invade (Verb) — Penetrate or assault, in a harmful or injurious way. ex. "The cancer had invaded her lungs"