keep quiet
hush up
keep
keep a lid on
keep one's lips sealed
keep one's mouth shut
keep to oneself
tick a lock
secret
keep one's counsel
let the cat out of the bag
cryptadia
button one's lip
disembosom
keep mum
give away
keep from
secrecy
on the Q.T.
in secret
secretly
keep shtum
conceal
on the QT
silence
secretiveness
stall
sensitive
concealment
covert
oyster
transpire
shut one's mouth
concealing
hiding
mum's the word
stifle
under wraps
between you and me
darkness
hush-hush
semisecretly
sing like a bird
cloakedly
evasive
secretness
semisecret
steal
one's lips are sealed
close ranks
hidingly
oversecrete
subterranean
confidentiality
keep shady
ulterior
secernent
subterraneous
closehandedness
unsecretly
under the covers
on the down-low
get wind of
inform on
secretively
sub rosa
backroom
secretive
confidable
hugger-mugger
closet
hideling
Deep Throat
underhand
hold one's tongue
on the hush
something nasty in the woodshed
confide in
lie low
closehanded
hidelings
hidness
tomb
feign
breast one's cards
antisecrecy
under one's hat
under the radar
guard one's tongue
private
disguise
aboveboard
straightforward
shoot off at the mouth