Nova because it just means 'new' isn't a term anybody can trademark.
Of course a trademark of a common word might arise naturally from being in the market and becoming widely recognized (e.g. Apple), but you can't file a trademark for it until you have become widely recognized.
This is why Nova is a very popular term for products.
The difficulty comes from the obligation to protect a trademark - if you have trademark rights to a term and don't take reasonable steps to protect it, you're at risk of losing your rights.