keep a lid on
cryptadia
under wraps
hush up
secret
concealing
hiding
concealment
keep from
under the covers
on the down-low
stall
closet
closehanded
on the hush
darkness
secrecy
backstage
silence
keep shady
secretiveness
subterranean
secretly
on the Q.T.
on the QT
in secret
closehandedness
secernent
confidentiality
sensitive
cloakedly
let the cat out of the bag
off-the-record
keep quiet
oversecrete
dark
conceal
hypersecrecy
semisecrecy
confidence
occulted
ultrasecret
hidness
sub rosa
concealedly
crypto-
secrete
under one's hat
hugger-mugger
lean
mum
privily
undisclosed
make known
tick a lock
keep
hiddle
feign
clandescent
shoot off at the mouth
underwrapped
lie low
in petto
keep one's lips sealed
obvelation
behind the scenes
let on
divulge
discover
uncover
expose
hush-hush
let out
disclose
semisecret
unwrap
give away
reveal
secretive
bring out
break
closeness
out
classify
under the rose
backroom
confide
something nasty in the woodshed
close-tiled
hypersecretory
underhand