"Steampunk is...set in a place and time where steam is the dominant form of high technology. It's a retro futurism," writes Cherie Priest. Boneshaker is just like that... a "steampunk zombie adventure". So, just to be clear, steampunk's distinctively defined by its use of technology.  Except the bits that are supernatural. Clear? Good. (Seattle Times found via Gail Carriger)