code namenoun [ C ]
uk/ˈkəʊd ˌneɪm/us/ˈkoʊd ˌneɪm/a special word or name that is used instead of the real name of someone or something to keep the real name secret:
Her code name is "Running Bear".
code-name
verb [ T ] uk/ˈkəʊd.neɪm/us/ˈkoʊd-/
[ + noun ] We've code-named the new project "Entropy".