1.Definition: (pathology) the spread of pathogenic microorganisms or malignant cells to new sites in the body

"The tumor's invasion of surrounding structures"

Category: General

2.Definition: any entry into an area not previously occupied

"An invasion of tourists", "An invasion of locusts"

Related Noun(s):encroachment, intrusion

Category: General

3.Definition: the act of invading; the act of an army that invades for conquest or plunder

Category: General