keep a lid on
cryptadia
secret
under wraps
hush up
under the covers
on the down-low
stall
keep from
concealment
keep quiet
subterranean
on the hush
hiding
closehanded
concealing
secrete
lean
keep shady
let the cat out of the bag
sensitive
underwrapped
feign
tick a lock
closet
hiddle
crypto-
mum
secrecy
out
occulted
conceal
secretly
keep one's lips sealed
lie low
darkness
secretiveness
silence
off-the-record
secernent
backstage
keep
secretive
pseudosecret
shadow
oversecrete
behind the scenes
closehandedness
under the rose
hypersecrecy
yield up
semiconceal
undisclosed
dark
concealedly
sub rosa
confidentiality
concealingly
mum's the word
cloakedly
shoot off at the mouth
keep to oneself
something nasty in the woodshed
hole up
in secret
feal
clandescent
make known
on the Q.T.
on the QT
ultrasecret
disembosom
masked
in petto
private
obvelation
hidness
semisecrecy
secretable
let something slip
close-tiled
spill the beans
doggo
open secret
undisclosedly
oyster
under the table
babble
give away
in hiding
out of sight
covert