incursion

When an army crosses a border into another country for battle, they are making an incursion into enemy territory. An incursion is an invasion as well as an attack.

Incursion can also be used to describe other things that rush in like an army such as an invasive species into a new region or floodwaters entering your home. When an airplane heads onto a runway it is not supposed to land on, risking airport safety, it is known as a runway incursion. And an incursion of cold air could make September feel like December.

Definitions of incursion
  1. noun
    the act of entering some territory or domain (often in large numbers)
    “the incursion of television into the American living room”
    see moresee less
    type of:
    entering, entrance, entry, incoming, ingress
    the act of entering
  2. noun
    an attack that penetrates into enemy territory
    synonyms: penetration
    see moresee less
    types:
    show 8 types...
    hide 8 types...
    interpenetration
    the action of penetrating between or among
    breakthrough
    a penetration of a barrier such as an enemy's defense
    invasion
    the act of invading; the act of an army that invades for conquest or plunder
    infiltration
    a process in which individuals (or small groups) penetrate an area (especially the military penetration of enemy positions without detection)
    foray, maraud, raid
    a sudden short attack
    air attack, air raid
    an attack by armed planes on a surface target
    inroad
    an invasion or hostile attack
    swoop
    a very rapid raid
    type of:
    attack, onrush, onset, onslaught
    (military) an offensive against an enemy (using weapons)
  3. noun
    the mistake of incurring liability or blame
    see moresee less
    type of:
    error, fault, mistake
    a wrong action attributable to bad judgment or ignorance or inattention
Word Family