MONIKER

mon ‧ i ‧ ker /ˈmɒnɪkə $ ˈmɑːnɪkər/ BrE AmE noun [countable] informal

[ Date: 1800-1900 ; Language: Shelta ; Origin: munnik , from Irish Gaelic ainm ]

a name, especially one that you choose for yourself or give something – used humorously