backdrop
background
barb
barbed
barrier
base
border
boundary
crime
criminal
danger
defending
escape
farm
fence
field
forbidden
freedom
garden
grass
green
growth
healthy
illustration
jail
lawn
locking
meadow
mesh
metal
natural
nature
penitentiary
perimeter
plant
police
prevent
prison
protection
safety
security
sharp
space
spring
steel
summer
white
wire
wired