[BetterRed]

We don't refer to a bricks and mortar library as a catalogue or card index. If you asked me about a calibre 'database', I might ask which 'database'?

All calibre libraries have at least two files which are regarded as 'databases' -- metadata.db and .calnotes.notes.db, and some libraries can have another two -- full-text-search.db and metadata_pre_restore.db.

Added: Dataset would be a good word to refer to a calibre library in the abstract.

BR