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

The city’s public works team and its Parks, Recreation and Marine bureau were working to secure it, putting up sandbags and rebuilding the berm to stop water intrusion. — Deborah Vankin, Los Angeles Times, 12 Oct. 2026

After a time, the normal chitchat and easiness of the room returned like a wound closing, the girls forgetting her intrusion. — Literary Hub, 9 Oct. 2026

This Best Buy set is great for small homes, with a quartet of entry sensors, a precise motion sensor, and a home hub with a loud 100 dB siren in case of intrusion. — K. Thor Jensen, PC Magazine, 9 Oct. 2026

The former Monty Python star’s criticism of Islam is a free-speech matter, not one for government intrusion. — Andrew Doyle, Washington Post, 7 Oct. 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)