What does SECRET mean?

adjective

1. not open or public; kept private or not revealed“a secret formula”
2. conducted with or marked by hidden aims or methods“clandestine intelligence operations”
3. not openly made known“a secret marriage”
4. communicated covertly“their secret signal was a wink”
5. not expressed“secret (or private) thoughts”
6. designed to elude detection“a hidden room or place of concealment such as a priest hole”
7. hidden from general view or use“a privy place to rest and think”
8. (of information) given in confidence or in secret“this arrangement must be kept confidential”