When reading on my iPad or Kindle (back when I had one of those), I would regularly encounter a word used in a context slightly different from my understanding of the word - so I'd quickly skim the definition to fill in the gap in my knowledge that this made apparent.

I _do_ miss that functionality on the reMarkable devices. It seems odd to me that it's not included; a dictionary isn't a huge file, and the devices have more than ample storage for their intended purpose. I used my daily for a couple of years, and I don't think I've ever deleted anything from them.