Patent and trademark law is a minefield. Although U.S. trademark law says that generic or geographic terms cannot be trademarked, try telling that to Apple, Amazon, even Lucid.
After retirement, my college linguistics professor had a very lucrative second career as a consultant for patent and trademark court cases. In discovery and at trial there could be reams of essays and hours of testimony on the origin of words, their changing use over time, regional differences in their use, whether or not a word had become genericized,
etc. His billing for a big case often ran into six figures, and he wasn't even one of the attorneys.
If you're really interested in the subject, you might start here:
What are generic terms, which are not protectable as trademarks, and how can an initially valid trademark become generic and unprotectable?
www.justia.com