Oh, it's so much more than word definitions! Just as an example, a recent book, Runnery Granary (which I highly recommend!) elicited the following discussions:

- what a water-wheel is
- why you grind grain
- whether goblins and gnomes are the same thing
- why this artist drew gnomes that look different than other people's ideas of gnomes
- what gnomes really look like (and why that's a hard question to answer)
- why the cats look tough and aggressive going into the granary
- why cats would be afraid of gnomes
- why one could infer that something bigger than rats was infesting the granary
- why the people would tiptoe when going into the infested granary at night
- why the gnomes don't look happy when they are stuck to the gnome-paper
- why the gnomes went looking for another granary when they finally got unstuck
- why the gnomes never came back to the first granary

Like I say, I've just gotten really zen about it -- this is what reading together is!