What does intruder mean?
An intruder is a person who enters a place, property, or system without permission. The term is especially common in security contexts, where it denotes someone who has gained or attempted unauthorized access to a building, restricted area, or electronic system. Figuratively, an intruder may be anyone who imposes on another person's privacy, conversation, or planned activity. The word generally carries a hostile or threatening connotation and is more specific than the neutral “visitor,” although it can occasionally sound formal or dramatic in ordinary descriptions of an unexpected guest. Its relatives—including intrude, intrusion, and intrusive—preserve the central idea of entering a space or sphere that is not properly one's own. Understanding the word therefore requires little etymological knowledge, but its Latin roots reinforce the image of a person forcibly pushing into an occupied or protected place.
nounA person who enters a place, property, or system without permission or authorization. The term can also refer figuratively to someone who intrudes into another person's space, activity, or privacy.
- A person who enters a place or property without permission or authorization.
- A person who intrudes upon someone's privacy, conversation, activity, or other territory.
"The security guard caught an intruder trying to enter the building through a side door."
"Motion sensors detected an intruder in the garden after midnight."
"She considered his questions about her private life an unwelcome intrusion."
Used for multiple unauthorized entrants; the plural can refer collectively to people attempting to enter or interfere.
"Two intruders attempted to cross the restricted area."
From the Latin verb intrudere, meaning “to thrust in,” an intruder began as someone who literally pushed their way inside.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does intruder come from?
The word dates from the late 16th century and comes from French intruder, derived from Latin intrudere, meaning “to thrust in” or “force one's way in.” Latin intrudere was formed from in-, meaning “into,” and trudere, meaning “push.” The same root produced intrude, intrusion, and intrusive, all of which preserve the idea of entering or pressing into something without a welcome.
How intruder is actually used
The word normally carries a negative or threatening connotation, emphasizing unauthorized entry or an unwelcome presence. It is used for physical security as well as figurative violations of privacy or boundaries.
Easily confused with intruder
An intruder is the person who enters without permission, whereas an intrusion is the act of entering without permission.
An invader typically enters with the intention of taking control or territory, while an intruder may enter only to gain unauthorized access.