Question :
Is there a term for all databases in SQL Server that are not system databases (such as master, model, tempdb)?
Answer :
The same “System” vs “User” distinction is also made for other objects such as tables.
Members of the db_datareader fixed database role can read all data
from all user tables.
msdb and the distribution database (if you use replication) are also system databases that you do not mention by the way.