#1 invasion n. the act of invading; the act of an army that invades for conquest or plunder. wn
#2 invasion n. [encroachment, intrusion] any entry into an area not previously occupied; "an invasion of tourists"; "an invasion of locusts". wn
#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
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