Other forms: intruders
An intruder is somebody who enters where they have no right to be. An intruder alarm, disturb an intruder, the intruder fled.
It is the standard word in police reporting and in the names of security products — intruder alarm, intruder detection. It implies entry without permission rather than theft, so an intruder need not have taken anything. Figuratively it means anybody unwelcome in a situation. Note intrude, intrusion; and intrusive, which describes questions and thoughts more often than people.
1nounintruderSomebody who enters where they have no right to be.
“The alarm went off when an intruder broke a window at the back of the house.”
intruder is an unauthorised entrant.
Proto-Indo-European
*trewd-
Latin
intrudere
English
intrude
English, today
intruder
Built from
From intrude + -er. intrude comes from Latin intrudere, from in- + trudere (“to thrust”).
Etymology from Wiktionary, CC BY-SA