The book says: it’s fruitless to try to take over a word that is already owned by a competitor. Burger King tried to own word “fast” which was already owned by McDonald; and failed miserably. FedEx tried to take over “worldwide” from DHL.
My comment: this talk about “owning” words is a bit silly. The book doesn’t say anything about how to actually own the word. I guess you’re supposed to use it in your marketing/advertisement material but such statement is not very helpful for a marketer (I think; I’m not one).
See also Eric’s take