Ah, no, different terms.

Cleanly shut down means that SQL had time to commit or roll back all active transaction and time to write all dirty pages to disk before either the SQL service was stopped, the database detached or taken offline. It means that no recovery process is needed when the DB starts up again.

There's nothing wrong with an unclean shutdown, SQL probably does those more often than clean ones (imagine shutting down the server while there's a transaction that's been running 3 hours active, SQL won't be allowed to take 3 hours before stopping)

Any time a database has been shut down (cleanly or not), it is safe to take the files (data and log) and attach elsewhere. It is not safe to copy the files of an active, online, in-use database.