Not 'export'...
BACKUP (and you should be doing this anywho

)
the USER dictionary(ies) reside in the Configuration folder along with all the other User settings (exception is those Per Library, which are embeded in the DB, so
BACK THE LIBRARY UP any time you make a setting change that invokes a #field name) and plugins'
Quote:
C:\Users\<yours>\AppData\Roaming\calibre\dictionar ies
|
is where both kinds are found: prefs.json is the users words, grouped by dict name.
The others are the Installed Dicts