invasion Meaning, Definition & Usage

  1. noun the act of invading; the act of an army that invades for conquest or plunder
  2. noun any entry into an area not previously occupied
    encroachment; intrusion.
    • an invasion of tourists
    • an invasion of locusts
  3. noun (pathology) the spread of pathogenic microorganisms or malignant cells to new sites in the body
    • the tumor's invasion of surrounding structures

WordNet

In*va"sion noun
Etymology
L. invasio: cf. F. invasion. See Invade.
Definitions
  1. The act of invading; the act of encroaching upon the rights or possessions of another; encroachment; trespass.
  2. A warlike or hostile entrance into the possessions or domains of another; the incursion of an army for conquest or plunder.
  3. The incoming or first attack of anything hurtful or pernicious; as, the invasion of a disease. Syn. -- Invasion, Irruption, Inroad. Invasion is the generic term, denoting a forcible entrance into a foreign country. Incursion signifies a hasty and sudden invasion. Irruption denotes particularly violent invasion. Inroad is entry by some unusual way involving trespass and injury.

Webster 1913