nickname
n. countablen. an informal name that your friends or family use for you instead of your real name. It is often shorter or based on something you do.
n. a familiar or humorous name given to a person or thing instead of the real name. Often derived from a diminutive form of the proper name or a specific personal characteristic.
My real name is Richard, but my nickname is Rick.
She earned the nickname 'Speedy' because she was the fastest runner on the school soccer team.
While some nicknames are affectionate terms used only within the family, others can become professional aliases that eventually replace the individual's legal name in public life.
From Middle English neke name, alteration (due to a rebracketing of an ekename as a nekename) of earlier ekename (“nickname”), from eke (“additional”) + name. Compare Old Norse aukanafn, auknafn, auknefni, Faroese eyknevni, Danish øgenavn, Norwegian Nynorsk aukenamn, Swedish öknamn, and German Low German Ökelname. For other similar cases of incorrect division, see also apron, daffodil, newt, orange, umpire.
Commonly takes the preposition 'for' when identifying the person it belongs to.