arrest
barrier
border
boundary
circles
convict
crime
criminal
danger
dangerous
escape
felon
fence
forbidden
freedom
frontier
guard
horizontal
ideas
illegal
immigration
imprisonment
jail
law
liberty
military
moody
obstacle
outlaw
police
prison
prisoner
privacy
private
problem
property
protect
protected
protective
quarantine
restricted
safety
secure
security
separation
steel
stormy
system
threats
war