Meaning of “secret” - Learner’s Dictionary

secret

adjective us uk /ˈsiːkrət/
They promised to keep her identity secret.He was spirited away to a secret hide-out in Mexico.They uncovered a secret plan to assassinate the politician.The prisoners are being kept at a secret location.The identity of the suspect is being kept secret.

B1 If something is secret, other people are not allowed to know about it:

a secret affair/meeting
I'll tell you but you must keep it secret.
secret admirer/drinker, etc

someone who does something or feels something without telling other people about it

secretly adverb

B1

He secretly taped their conversation.

See also

(Definition of “secret adjective” from the Cambridge Learner’s Dictionary © Cambridge University Press)