The word for today is…
sobriquet (noun) – 1. An affectionate or humorous nickname.
2. An assumed name.
Source : The Free Dictionary
Etymology : This synonym of nickname has the same meaning in modern French as it does in English. In Middle French, however, its earlier incarnation soubriquet referred to both a nickname and a tap under the chin. Centuries later, the connection between these two meanings isn’t clear, but what is clear is that the “nickname” meaning of sobriquet was well established in French by the time English speakers borrowed the term in the 17th century—and was the only meaning that was adopted. In current English, the spelling sobriquet is most common, but soubriquet is also an accepted variant.