block
blocked
close
closed
commerce
crisis
difficulty
dirt
dirty
door
economic
entry
finance
financial
fit
gold
key lock
locked
locker
macro
metal
metaphor
old
open
padlock
password
problem
prohibited
proof
protect
protection
puzzle
question
rust
safety
secret
secure
security
set
shiny
solution
steal
steel
success
theft
thief
unauthorized
yellow