definition of
invasion

[1] #1 invasion n. the act of invading; the act of an army that invades for conquest or plunder. wn

[2] #2 invasion n. [encroachment, intrusion] any entry into an area not previously occupied; "an invasion of tourists"; "an invasion of locusts". wn

[3] #3 invasion n. (pathology) the spread of pathogenic microorganisms or malignant cells to new sites in the body; "the tumor's invasion of surrounding structures". wn