secrecy
practice of hiding information or making it inaccessible; quality of such information
privacy
ability or right of an individual or group to seclude themselves, or information about themselves
conspiracy
secret plan or agreement for an unlawful or harmful purpose, especially with political motivation
pseudonymity
state of disguised identity in which a pseudonym identifies one or more human beings who do not disclose their legal identities
family secret
secret kept within a family
medical privacy
practice of maintaining the security and confidentiality of patient records
clandestine HUMINT
type of intelligence activity
anonymity
quality of a person who is non-identifiable, unreachable, or untrackable
professional secrecy
rules applied to some professional of not revealing confidential information to any unauthorized third party, and of protecting and restricting them against any unlawful access