intrusion

noun

in·​tru·​sion in-ˈtrü-zhən 

1

: the act of intruding or the state of being intruded

especially : the act of wrongfully entering upon, seizing, or taking possession of the property of another

2

: the forcible entry of molten rock or magma into or between other rock formations

also : the intruded magma

Examples of intrusion in a Sentence

Recent Examples on the Web

In its lawsuit, Citrus Heights said city police had responded to a disproportionate number of calls to the property, and that there was widespread water intrusion. —Sacbee.com, 7 Mar. 2026

Its partner, the Occulter spacecraft, blocks out the bright disk of the sun's face in order for the Coronagraph to image the corona without the intrusion of blinding light from the star. —Josh Dinner, Space.com, 6 Mar. 2026

Many of the chemicals found beneath Atlas evaporate at room temperature and sneak into buildings through cracks in foundations, floor drains or other gaps — a process known as vapor intrusion. —Tony Briscoe, Los Angeles Times, 5 Mar. 2026

The intrusion of warm water below the ice sheets explains most of the retreat patterns in Western Antarctica, but the significant grounding line migration along the Antarctic Peninsula, which sits on the northeast part of the continent, is not as clear, the researchers said. —Julia Jacobo, ABC News, 5 Mar. 2026

Word History

Etymology

Middle English, from Anglo-French, from Medieval Latin intrusion-, intrusio, from Latin intrudere

First Known Use

15th century, in the meaning defined at sense 1

Phrases Containing intrusion

• anti-intrusion

Rhymes for intrusion

• allusion
• collusion
• conclusion
• confusion
• contusion
• delusion
• diffusion
• effusion
• exclusion
• extrusion
• illusion
• inclusion

Kids Definition

intrusion

noun

in·​tru·​sion in-ˈtrü-zhən 

1

: the act of intruding : the state of being intruded

2

: the entry by force of melted rock into or between other rock formations

Legal Definition

intrusion

noun

in·​tru·​sion in-ˈtrü-zhən 

1

a

: the entry at common law of a stranger after a particular estate of freehold is determined before the person who holds it in remainder or reversion has taken possession

b

: the act of wrongfully entering upon, seizing, or taking possession of the property of another

2

: a trespassing on or encroachment upon something (as a right)

the Fourth Amendment demands that the showing of justification match the degree of intrusion

—Berger v. New York, 388 U.S. 41 (1968)