Genericide: The process by which a brand name becomes a generic name for the entire brand category. (It's an awkward neologism; strictly speaking, the word means "death of a generic term," just as regicide means the killing--in Latin, cidium--of a monarch--regis.) Word Spy offers some examples of trademarks that became generics: aspirin, yo-yo, escalator, and so on. And Seth Godin discusses "the paradox of a trademark":
Every trademark that turns generic does so for the same reason: because it's the easiest way to describe something. People didn't say, "That's a sexy Bikini® brand bathing suit." Because the idea itself was bigger (or smaller) than a bathing suit, the new thing needed a name. And the name we picked was bikini.
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The best thing you can invent, as far as I can tell, is an idea that needs a name. When they invented the Jeep®, there was no such thing as the SUV. The Jeep became the name for that idea. The lawyers at Chrysler worked superhard to keep the brand from becoming generic. When the engineers cooked up the Xerox®, they had the same problem. Now, people are happy to call it a copier.
You can recover from impending genericide. What you can't recover from is a clumsy name, or hindering your idea so it doesn't spread or coming up with a slightly better idea for something that already has a quite good enough name and idea.