1. (

• invasion

) the act of invading; the act of an army that invades for conquest or plunder ;

2. (

• invasion ,
• encroachment ,
• intrusion

) any entry into an area not previously occupied; "an invasion of tourists"; "an invasion of locusts" ;

3. (

• invasion ,

) (pathology) the spread of pathogenic microorganisms or malignant cells to new sites in the body; "the tumor's invasion of surrounding structures" ;