Onyx Poke5 BOOX User Manual page 58

You can import your own dictionary files and save them to the
designated storage path: sdcard\dicts\XXX;
Each dictionary has a corresponding folder. For example,
dicts\Advanced Chinese Dictionary
In dictionary Settings/Preferred Dictionary Setting, you can check all
available dictionaries. Up to 20 dictionaries are supported.
When there are dictionaries installed, you can search words in the
search box. The lookup results are subject to the words included in
the dictionary. If you cannot find a word, please change to another
dictionary.
You can add found words to Vocabulary Builder to manage in bulk.