ハンドルネーム

はんどるねーむ
noun
online handle; username; screen name
internetcommunication
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.
ハンドルネーム投稿(とうこう)する
Post under a handle.
Use a handle rather than your real name.
On the forum, I only know him by his handle.

Wasei-eigo (Japanese-coined English) from "handle" + "name"; natural English would be "username," "screen name," or "handle." Commonly abbreviated HN.

Common collocations

Similar words