Dictionnaire pour les Français

You can, if you wish to go to the trouble, replace Scrivener’s dictionaries with others in hunspell format.

If you’ve done this already, don’t read the rest…

  • the replacement names must be spelled EXACTLY the same as the originals. I am not sure capitals make a difference, but an underscore instead of a dash or vice versa will break them.
  • When Scrivener updates, it may replace them, so keep a copy hanging around.

And at [url][JH] Dictionaries - Portuguese - #6 by Aristoteles] are instructions for replacing, if you want further reading.