invasion

American  

[in-vey-zhuhn] / ɪnˈveɪ ʒən /

noun

1. an act or instance of invading or entering as an enemy, especially by an army.

2. the entrance or advent of anything troublesome or harmful, as disease.

3. entrance as if to take possession or overrun.

   the annual invasion of the resort by tourists.

4. infringement by intrusion.

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invasion British  

/ ɪnˈveɪʒən /

noun

1. the act of invading with armed forces

2. any encroachment or intrusion

   an invasion of rats

3. the onset or advent of something harmful, esp of a disease

4. pathol the spread of cancer from its point of origin into surrounding tissues

5. the movement of plants to a new area or to an area to which they are not native

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Other Word Forms

• preinvasion adjective
• reinvasion noun

Etymology

Origin of invasion

1400–50; late Middle English < Late Latin invāsīon- (stem of invāsiō ), equivalent to invās ( us ), past participle of invādere + -iōn- -ion; invade

Explanation

An invasion is the movement of an army into a region, usually in a hostile attack that's part of a war or conflict. World history is full of descriptions of invasions. One country's army plundering or taking over a city or piece of land in another country is an invasion. You can call other mass movements invasions as well, like a horrifying invasion of your kitchen by cockroaches, or the invasion of a stadium by excited soccer fans. A common phrase is "invasion of privacy," which means an unfair intrusion into someone's personal space or private information.

Example Sentences

He cited the Gulf War in 1990 involving Iraq’s surprise invasion of Kuwait as the “closest analog to the current environment when it comes to how oil prices affect U.S. equity valuations.”

From MarketWatch • Apr. 14, 2026

Wright said demand for the charity's services initially rose when the cost of living crisis began following Russia's invasion of Ukraine in 2022, which saw the price of oil, gas and agricultural products soar.

From BBC • Apr. 10, 2026

Prices spiked following previous disruptions during the financial crisis of 2008 and the Russian invasion of Ukraine in 2022.

From Barron's • Apr. 10, 2026

The stock’s biggest spikes in that time came during the 2022 energy crisis following Russia’s invasion of Ukraine and the current global shock; it opened at $191.41 on Wednesday.

From The Wall Street Journal • Apr. 8, 2026

Most Austrians were ethnically Germanic, and this wasn’t an invasion of their country.

From "A Thousand Sisters" by Elizabeth Wein

Related Words

• aggression
• assault
• breach
• incursion
• infiltration
• infringement
• intrusion
• offensive
• onslaught
• raid
• violation