Could you please give me more details on plugins for bulk imports?
I have tried to use the Ultimate CSV Importer plugin and I am only able to select Explanatory Dictionary as a custom post type for the ID column. I therefore get an error when trying to import as I can’t select a field Type for the other columns (word, synonyms_and_forms, explanation)
The explanation is the normal editor field (post_content) so you should be able to fill that during the import.
As for the custom meta_box (synonyms) I’m not sure how that Ultimate CSV Importer plugin works, but I’ve just created a custom post type and added the meta_box as WP explains it to so if it doesn’t work I think that the problem lies within the importer.
Now I might look into this in the future but for now I wont