Moniker, sobriquet (8)
I believe the answer is:
nickname
I believe this is a double definition.
'moniker' is the first definition.
(I know that moniker can be written as nickname)
'sobriquet' is the second definition.
(I know that sobriquet can be written as nickname)
(Other definitions for nickname that I've seen before include "Jack the Ripper, for example" , "Add soubriquet to" , "Cognomen" , "Agnomen" , "term for someone" .)