Thank you to Burn.Life for their wonderful Preparing and Attending guides.
Here's the link to their packing lists, nicely done!
There's no such thing as a 'definitive' packing list for Burning Man. What you're bringing depends on what kind of thing you're staying in (tent? yurt? box truck? RV?) and what your requirements are both for your individual survival and enjoyment, and for how you're going to contribute to your camp (if you're part of one) and Burning Man at large.
Having said that, here are a couple packing lists to help guide you.