secretname
nounUK /ˈsiː.krət.neɪm/
US /ˈsiː.krət.neɪm/
A secretname is a special name you keep hidden and only share with people you trust.
Only her best friend knew her secretname.
OTHER MEANINGS
2. A made-up name a person uses online so nobody knows who they really are.
He picked a secretname for his game account.
3. A special name that only members of a club are allowed to know.
The treehouse club gave every member a secretname.
4. A name kept hidden to protect someone or something.
The spy wrote her secretname in a tiny notebook.