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 some places, levels are the lowest in more than a decade, which can increase the risk of saltwater intrusion in freshwater supplies. —Jenny Staletovich, Miami Herald, 7 Feb. 2026

This was bound to result in agent intrusions into homes and businesses, since there aren’t that many criminal migrants to fill such a quota each day. —The Wall Street Journal, Twin Cities, 6 Feb. 2026

Blocking near the Arctic and repeated intrusions of cold air into central and eastern North America suggest winter may ease at times but is unlikely to end abruptly across Ohio. —Brandi D. Addison, Cincinnati Enquirer, 3 Feb. 2026

Meanwhile, the Climate Prediction Center’s long-term outlook indicates the possibility of Arctic air intrusions through at least early March, linked to a polar vortex split or sudden stratospheric warming event. —Brandi D. Addison, IndyStar, 3 Feb. 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)