1. secret names or code names used to conceal the true identity of a person, place, or operation
Usage: plural form

Examples

• Intelligence agencies often use cryptonyms to protect the identities of their operatives.
• The military operation was known only by its cryptonym until it was declassified years later.
• Historians discovered that several famous writers had published under cryptonyms.
• The spy network communicated using a system of cryptonyms for all personnel.
• Government documents revealed cryptonyms for various Cold War projects.
• The resistance fighters adopted cryptonyms to protect their families from retaliation.