intrusion

American  

[in-troo-zhuhn] / ɪnˈtru ʒən /

noun

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

• intrusional
  adjective

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

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

These included expanding the enclosure's viewing restriction area and installing intrusion prevention nets, it said.

From BBC • May 18, 2026

The enormous intrusion unfolded within just a few days and involved enough magma to fill roughly 32,000 Olympic-sized swimming pools.

From Science Daily • May 14, 2026

The intrusion of e-bikes is sparking a fierce backlash from traditional trail users and forcing land managers into a confusing new debate over safety and fairness.

From Los Angeles Times • Apr. 17, 2026

The couple, who have two children, have long complained about media intrusion and Meghan's treatment by Britain's newspapers after years of negative stories.

From Barron's • Apr. 14, 2026

And whereas before, her mother’s and Jaimito’s mother’s hints were the intrusion of elders into what was none of their business, now it seems the old people were perceiving destiny.

From "In the Time of the Butterflies" by Julia Alvarez

Related Words

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