|1.||[ noun ] (military) the act of invading; the act of an army that invades for conquest or plunder|
|Related terms:||penetration inroad invade|
|2.||[ noun ] any entry into an area not previously occupied|
"an invasion of tourists" "an invasion of locusts" "a viral invasion"
|Related terms:||entrance encroach|
|3.||[ noun ] (pathology) the spread of pathogenic microorganisms or malignant cells to new sites in the body|
"the tumor's invasion of surrounding structures"
|Related terms:||spread medicine|