covered
inhibited
arcane
bated
cabalistic
censored
classified
close
closed
concealed
crushed
cryptic
damped
dampened
dark
dead
deadened
dull
dulled
enigmatic
esoteric
flat
hermetic
hidden
hush-hush
latent
muffled
muted
mysterious
occult
quashed
quelled
repressed
restricted
secret
smashed
softened
sordo
squashed
squelched
stifled
subdued
suffocated
suppressed
top secret
ulterior
unbreatheable
under security
under wraps
undisclosable
undisclosed
undivulgable