keep
keep quiet
keep to oneself
hush up
shut one's mouth
keep one's mouth shut
keep one's lips sealed
give away
disembosom
breast one's cards
secretly
in secret
on the QT
on the Q.T.
secrecy
undisclosedly
keep a lid on
let the cat out of the bag
revealing
telling
telltale
oversecrete
keep from
secret
mum's the word
keep shtum
confidentiality
steal
darkness
silence
secretiveness
confide
cryptadia
restrict
between you and me
unsecretly
secernent
secretive
semisecret
under wraps
make known
unmuffle
sensitive
evasive
undisclosed
keep mum
closet
keep one's counsel
conceal
hiding
concealment
concealing
privily
straightforward
stall
confidable
aboveboard
ulterior
stifle
disguise
subterranean
subterraneous
transpire
semisecretly
one's lips are sealed
hypersecrete
superarcane
undisclosing
secretively
giveaway
cloakedly
sing like a bird
closehandedness
babble
self-edit
hiddle
hypersecrecy
under the radar
something nasty in the woodshed
betray
hidness
confidentially
underhanded
confidence
secretness
sub rosa
hiss-and-tell
under one's hat
tick a lock
leak
unbosom
mum
hugger-mugger
relieve