access
arcana
authorized
classified
concept
conceptual
confidential
confidentiality
espionage
forbidden
hashish
hidden
hush
information
insight
insightful
intelligence
paper
penetration
perceive
perception
perceptiveness
perspicacity
privacy
private
privy
protect
protection
receptivity
restricted
safety
secluded
secrecy
secret
secure
security
spy
text
top
torn
under
undercover
underground
undisclosed
unknown
unpublished
unrevealed