In plain English
It means someone else is already using that exact account name. Because a username can belong to only one account at a time, this one cannot be chosen.
In context
Here, it reports that the username entered is already in use by another account, so it is not available.
- Situation
- Managing profiles, usernames, privacy, audience, discoverability, and account visibility
- What it communicates
- reports that the entered username is already in use
Meaning limits
By itself, this status does not identify the other account or explain anything beyond the selected username not being available.
Examples
“Her first choice was rejected because the username was taken, not because it broke any naming rule.”
“When the username is taken, the user enters a different one and tries again.”