abstract
access
background
barbs
barrier
beams
boundary
break
captivity
cloud
coil
concept
crime
cross
danger
dangerous
defense
detention
enclose
enclosed
enclosure
escape
freedom
galvanised
imprisoned
iron
mesh
metal
military
object
obstacle
perimeter
prevent
prevention
prison
privacy
private
protect
protection
razor
safety
secure
security
shine
sky
steel
sun
sunrise
twisted
war
wire