I guess definition is the wrong word, but [Bob McKay] splits research out in three categories:
1. Memory (research from what you know / have experience)
2. Imagination (research from noodling)
3. Fact (research in books etc.)
Hey, I LIKE that. It explains a lot of things, actually. Everything you'll ever write about is covered by one of those categories or a combination thereof. And the whole "write what you know" chestnut - which, if believed, would consign the ENTIRE genre of fantasy and science fiction to the flames - becomes a lot more manageable...
Back to your regularly scheduled entertainments now. More later. Maybe.