You and the other commenters who are saying this know that... devices can do multiple things, right? That's why phones don't just call people anymore.

Anyway, I don't really see why reading a PDF means one wouldn't need a dictionary. A lot of PDFs - that I read anyway - tend to be more technical stuff; looking stuff up is helpful there too.

I’m a little surprised at the pushback, too. I read lots of things on other devices where it’s easy to select a new word and see its meaning. And it seems like such an incredibly cheap feature to implement and support that I can’t imaging not having it.