Translation guide
A code name is a substitute name used to conceal identity, project, or operation. In Japanese, the most common equivalent is コードネーム, a direct loanword. Other options include 暗号名 (formal, military) and 秘匿名 (rare, literary).
What is the code name?
A name used to hide the real identity of a person, project, or operation.
コードネーム is widely understood and can be used in most situations. For formal documents or military contexts, 暗号名 may be more appropriate. Avoid 秘匿名 unless you are writing a novel or historical text.
The code name for this operation is 'Operation Blue'.
The most common and neutral term, used in business, military, and casual contexts. A direct loanword from English.
The code name for this project is 'Sunrise'.
Literally 'cipher name'. More formal and often used in military or intelligence contexts. Can sound technical.
The spy's code name was 'Nightfall'.
A rare, literary term meaning 'secret name'. Not commonly used in everyday speech.
He operated under a code name.