As I read papers, I often come across new terminology that I have to look up. I then usually add a comment that includes the definition for the term. However, since my memory is shot, it often happens that two pages later (or when I come back to the paper a few days later), I’ve already forgotten what the term means. Consequently, it would be nice if there was a “definition” category that one could use for a highlighted word. Then, ideally, one could hover over the same word (or word stem) later in the paper and see the definition that was added earlier. This feature would be even more useful if that definition could be seen in other papers entirely.
This is a feature I haven’t seen in any other reference manager, so kudos to you if you implement it.