This plugin for KOReader has the functionality to create notes for terms or phrases and display them in other occurrences.
Details and source are on this link:
https://github.com/omer-faruq/memobook.koplugin
Basic workflow:
- Create a note for a word or word group.
- See these notes on other occurrences.
- Set aliases to see the same note for other variations of the word.
- You can set some books to use the same notes on them. ( for series, etc. )
Tested on Kobo Forma, Kindle Touch, and Ubuntu