invasion

Noun

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

• any entry into an area not previously occupied
  • an invasion of tourists
    
  • an invasion of locusts
    

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

Related words

• Synonyms: 
  encroachment , intrusion