秘密

The meeting was held/conducted in secrecy.

secret meeting place; secret rendezvous

secret talks/trial/diplomacy

steal a marriage

This is to be kept strictly hush-hush.

This is a secret, and if you repeat it to anyone I'll kill you.

We eventually managed to worm the secret out of him. / We eventually wrested the secret from him.

He is in/on the secret.

The secret got out.

bosom secret

trade secret

open/public secret

lock a secret in one's breast/heart

disclose/expose/yield a secret; let out/give away a secret

tell secrets (to sb); let sb in on the secret; take sb into a/the secret

offer secrets (to sb)

explore the secrets (of)

unravel the secrets (of)

steal secrets

pry into a secret

ferret out state/military secrets

smell out secrets

keep/hold a secret; keep sth under one's hat