alarm
alertness
barb
barrier
border
building
cable
cam
camera
cctv
circuit
closed
closeup
control
crime
danger
data
detection
electric
electronic
enforcement
equipment
exterior
eye
guard
jail
lens
lockup
look
monitor
observation
observe
outdoor
overhead
precaution
prison
prisoner
privacy
private
protection
record
safety
security
spy
surveillance
system
technology
television
tower
video
visual
wall
watch
watching
watchtower