Surnom vs. pseudo

In French, both 'surnom' and 'pseudo' refer to the concept of a nickname, but they are used in different contexts and have different connotations. The following sections will explain the nuances between these two terms.

Surnom

A nickname that is usually given based on personal characteristics or specific incidents, often used among friends, family or acquaintances.
Le 'Lion de Corinthe' est le surnom donné à l'athlète pour sa force.
('The Lion of Corinth' is the nickname given to the athlete for his strength.)
Ils m'ont donné un surnom très blessant.
(They gave me a very offensive nickname.)
Dans le milieu scolaire, il était connu sous le surnom de 'Doc' à cause de son intelligence.
(In school he was known by the nickname 'Doc' because of his intelligence.)

Pseudo

A pseudonym used particularly in virtual contexts such as forums, gaming, social networks, or for artistic purposes. It can provide anonymity or create an alternate identity.
Sur ce forum, mon pseudo est 'Phoenix123'.
(On this forum, my username is 'Phoenix123'.)
Elle utilise le pseudo 'MysticPainter' pour partager ses œuvres en ligne.
(She uses the alias 'MysticPainter' to share her artwork online.)
Quand il publie des poèmes, il signe sous le pseudo de 'NuitEtoilée'.
(When he publishes poems, he signs under the pseudonym 'StarryNight'.)

Summary

'Surnom' is a nickname that reflects a characteristic or notable trait and is used more in real-life social interactions. On the other hand, 'pseudo' often refers to an online or artistic moniker aimed at preserving one's anonymity or expressing an alter ego. Both articulate alternate identities beyond one's formal name but differ mainly in their usage contexts — personal and physical for 'surnom', and digital or artistic for 'pseudo'.