codename
nounUK /ˈkəʊd.neɪm/
US /ˈkoʊd.neɪm/
A codename is a secret name used to hide who or what something really is.
The spies used a codename so nobody would know their real names.
OTHER MEANINGS
2. A name given to a secret military or government operation.
The rescue mission had the codename 'Operation Sunrise.'
3. A name used for a product while it is being developed in secret.
The new phone was known by the codename 'Project Star' before launch.
4. To give someone or something a secret name.
The team codenamed the plan 'Bluebird' to keep it hidden.