Hi again! So this is more broadly about setting than the definitions list assignment, but it does touch on it a bit, so here! "Setting of a Story"  

Definitions are important, and I promise you from personal experience, that saying to yourself, "oh I'll remember when I write the story, it's fine" might work, but probably will not.

For fantasy, there's always the rules of magic to consider, but some other things you could consider are: magical creatures- what kind and how do they work, is technology a thing in your fantasy or did you leave it at the door, are there different kinds of magic users in your story and is there anything you want to remember about them. Any magical amulets lying around? Magic swords? Magic guns?

For non-fantasy, there are always things to consider like: what kind of organizations exist and what are their guidelines, what companies are important, if your protagonist doesn't work, are they on disability? you could research how that works for the country they're in, what kind of disabilities they have/what symptoms. Family heirlooms could be an object!

"Whoever fights monsters should see to it that in the process he does not become a monster. And when you look long into the abyss, the abyss also looks into you."-Nietzsche