From the book What If? of XKCD when talking about super strong winds:
The flying debris would pulverize anything that wasn't nuclear-hardened.
What does nuclear-hardened mean? The closest result from Google for this term is Radiation hardening. But radiation hardening simply means making a device withstand-able in high radiation environment. The context doesn't mention anything about radiation, or radiation wind (if it even exists), just air wind.
So what does nuclear-hardened mean?