intrusion

American  

[in-troo-zhuhn] / ɪnˈtru ʒən /

noun

• intrusions
  plural

1. an act or instance of intruding.

2. the state of being intruded.

3. Law.

   1. an illegal act of entering, seizing, or taking possession of another's property.

   2. a wrongful entry after the determination of a particular estate, made before the remainderman or reversioner has entered.

4. Geology.

   1. emplacement of molten rock in preexisting rock.

   2. plutonic rock emplaced in this manner.

   3. a process analogous to magmatic intrusion, as the injection of a plug of salt into sedimentary rocks.

   4. the matter forced in.

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intrusion British  

/ ɪnˈtruːʒən /

noun

1. the act or an instance of intruding; an unwelcome visit, interjection, etc

   an intrusion on one's privacy

2. 1. the movement of magma from within the earth's crust into spaces in the overlying strata to form igneous rock

   2. any igneous rock formed in this way

3. property law an unlawful entry onto land by a stranger after determination of a particular estate of freehold and before the remainderman or reversioner has made entry

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intrusion Scientific  

/ ĭn-tro̅o̅′zhən /

1. The movement of magma through cracks in underground rocks within the Earth, usually in an upward direction.

2. ◆ Rocks that form from the underground cooling of magma are generally coarse-grained (because they cool slowly so that large crystals have time to grow) and are called intrusive rocks.

3. Compare extrusion

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Other Word Forms

Derived Forms

• intrusional
  adjective

Inflected Forms

Nouns

• intrusions
  plural

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Etymology

Origin of intrusion

1250–1300; Middle English < Medieval Latin intrūsiōn- (stem of intrūsiō ), equivalent to Latin intrūs ( us ), past participle of intrūdere to intrude (equivalent to intrūd- verb stem + -tus past participle suffix, with dt < s ) + -iōn- -ion

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Explanation

An intrusion is a deliberate move into someone else's territory — either literal or figurative. When your sister interrupts your conversation with that girl from math class, that's an intrusion. If someone breaks into your home, that's also an intrusion. First used in the late 14th century, the noun intrusion derives from the Latin word intrudere, which combines the prefix in-, meaning "in," and trudere, meaning "to thrust, push." If someone reads your diary, that's considered an intrusion of privacy. Ordering a Muslim woman to take off her veil would be considered an intrusion on religious beliefs. You may remember intrusion used in science class to describe molten rock that forms in an earlier rock formation.

Example Sentences

See Examples For:

intrusion intrusions

City crews are pumping out water on the streets, rebuilding beach berms and opening tide valves to help mitigate water intrusion.

From Los Angeles Times ● Oct. 9, 2026

It later called the intrusion a “marketing campaign” and said it wouldn’t publish the stolen data.

From Slate ● Sep. 30, 2026

The researchers identified a large thermal gradient, with temperatures reaching approximately 350 degrees Celsius beside the magma intrusion and falling to about 72 degrees Celsius at an ancient seafloor asphalt spill roughly 300 meters higher.

From Science Daily ● Sep. 26, 2026

It will be a constant intrusion in your life.

From MarketWatch ● Sep. 21, 2026

Suddenly it all feels like the worst kind of intrusion.

From "How It Went Down" by Kekla Magoon

Hackers used a Chinese artificial-intelligence agent to attack South Korea’s biggest banks and steal the personal information of 68,000 people, officials said, marking one of the first such AI-powered intrusions into the global financial system.

From The Wall Street Journal ● Oct. 6, 2026

Companies tolerated these intrusions because the finances of their businesses were still good enough.

From The Wall Street Journal ● Oct. 1, 2026

"Security personnel have had to deal with intrusions and the police have been contacted on numerous occasions," he added.

From BBC ● Sep. 9, 2026

For some soccer fans, though, the commercial breaks are an intrusions.

From Los Angeles Times ● Jun. 16, 2026

Such intrusions are so common that Border Patrol agents advise ranchers to leave water and food outside, beside their doors.

From "Enrique's Journey" by Sonia Nazario

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Related Words

• encroachment
• imposition
• incursion
• interference
• intervention
• invasion

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