1.
name used online instead of one's real name
A nickname a person uses on the internet—on forums, social media, games, or chat—in place of their real name. A Japanese coinage (wasei-eigo) from English "handle" + "name"; often abbreviated HN.
Wasei-eigo (Japanese-coined English) from "handle" + "name"; natural English would be "username," "screen name," or "handle." Commonly abbreviated HN.