intruders
Unwelcome boundary crossers
Intruders are people who enter where they don't belong—typically a building, property, or space where they have no right to be.
The word usually implies unwelcome presence and possible threat: The alarm system detected intruders.
Security systems, guard dogs, and warning signs all address potential intruders.
The term extends to anything that encroaches where it shouldn't: Invasive species are intruders in native ecosystems.
One who breaks in
- thiefOne who steals
- housebreakerOne who breaks in
- break-inUnlawful entry to premises
- robberyTheft through intimidation
prowler · home invasion · trespasser · masked · forced entry · window · lock · stolen
Unlawful entrant on property
- gatecrasherUninvited event attendee
- uninvitedWithout formal welcome
- interloperOne who enters uninvited
- squatterUnauthorized building inhabitant
poacher · snooper · encroacher · meddler · unwanted · stalker · loiterer · crasher
Urgent warning signal
- surveillanceSystematic observation of subjects
- cameraImage capturing device
- sensorInput-detecting device
- barrierObstruction preventing passage
gate · monitoring · protection · defense · firewall · access control · biometrics · motion detector
One who enters aggressively
- conquerorVictor who takes control
- armyOrganized land-based military
- occupationOne's regular paid work
- incursionHostile territorial penetration
siege · assault · territory · colonizer · imperialism · annexation · encroachment · raider
Unauthorized system accessor
- malwareHarmful computer programs
- virusMicroscopic infectious agent
- cyberattackMalicious digital intrusion
- breachBreaking of agreement
unauthorized access · phishing · spyware · ransomware · backdoor · exploit · cybercriminal · botnet
Being from outer space
- UFOUnidentified aerial craft
- RoswellNew Mexico city, UFO-famous
- Area 51Classified Nevada test facility
- E.T.Extraterrestrial being
abduction · spaceship · otherworldly · first contact · sci-fi · invasion · bodysnatchers · probe
burglar
One who breaks in
- thiefOne who steals
- housebreakerOne who breaks in
- break-inUnlawful entry to premises
robbery · prowler · home invasion · trespasser · masked · forced entry · window · lock · stolen · police
trespasser
Unlawful entrant on property
- gatecrasherUninvited event attendee
- uninvitedWithout formal welcome
- interloperOne who enters uninvited
squatter · poacher · snooper · encroacher · meddler · unwanted · stalker · loiterer · crasher · pest
alarm
Urgent warning signal
- surveillanceSystematic observation of subjects
- cameraImage capturing device
- sensorInput-detecting device
barrier · gate · monitoring · protection · defense · firewall · access control · biometrics · motion detector · perimeter
invader
One who enters aggressively
- conquerorVictor who takes control
- armyOrganized land-based military
- occupationOne's regular paid work
incursion · siege · assault · territory · colonizer · imperialism · annexation · encroachment · raider · expeditionary
hacker
Unauthorized system accessor
- malwareHarmful computer programs
- virusMicroscopic infectious agent
- cyberattackMalicious digital intrusion
breach · unauthorized access · phishing · spyware · ransomware · backdoor · exploit · cybercriminal · botnet · firewall
extraterrestrial
Being from outer space
- UFOUnidentified aerial craft
- RoswellNew Mexico city, UFO-famous
- Area 51Classified Nevada test facility
E.T. · abduction · spaceship · otherworldly · first contact · sci-fi · invasion · bodysnatchers · probe · sighting
- unwelcome peopletrespassers, invaders, uninvited guests, gatecrashers, crashers
- night terrorsnightmares, bogeymen, sleep paralysis, ghosts, phantoms
- annoying peoplepest, hecklers, nuisance, meddlers, bore
- fearsspiders, snakes, falling, heights, death
- things to fight offillness, infection, cold, flu, disease
- infringerspirates, plagiarists, counterfeiters, bootleggers, forgers
intrudersinvited guests
Those formally requested present
guests · invitees · visitors · company · houseguests
intrudersrightful owners
residents · inhabitants · occupants · insiders · homeowners
- intruder alarmUnauthorized entry detector
- intruder drillPractice for unwelcome entry