keep from
divulgence
ultrasecret
top secret
divulgement
secretiveness
occulted
purdah
under wraps
keep quiet
keep one's mouth shut
shut one's mouth
disembosom
industrial espionage
something nasty in the woodshed
privily
underwrapped
underhanded
secretomal
supersecrecy
nonsecretion
supersecret
ulterior
furtive
secret
let the cat out of the bag
hypersecreting
close
between you and me
closemouthed
semisecretly
espionage
a man's home is his castle
secretional
on the down-low
confidence
secretionary
back door
secretogenic
tightlipped
on the hush
under the covers
closelipped