For french dictionary, Kobo has switched a few years ago from Larousse to the "Robert micro 2013" which is still a pocket dictionary for french middle school / grammar school.
So, it's still ridiculous ( although I am surprised to find in it some words I didn't know ).
But with newest kobo firmware versions, you can add your own free dictionaries, e.g. :
Littré 1876 : 80 000 entries ( includes ethymology + examples of usage in french literature )
Académie Francaise 1935 : 35 000 entries ( using same definitions as Littré )
Wiktionnaire ( updated every night ) : 327 000 entries ( also includes proper names and ethymology )
downloadable from
https://github.com/BoboTiG/ebook-reader-dict
You also have versions for english, german, spanish, catalan, etc ...
To be compared with the 35 000 short entries of the embedded Robert Micro .
If you read old classics ( Dumas, Balzac, Hugo, etc ) , the Robert Micro is not enough, you need at least Littré or Wiktionnaire.
And lastly, if you need more thorough explanations, you can search wikipedia over wifi with Kobo.