There is a moment every marketer both dreams of and fears. It is the time when a brand name, by decree of the dictionary or whims of the zeitgeist, becomes a common noun or a verb. This can be a blessing—the ultimate validation of a name that is both catchy and meaningful. But it can also be a curse. The more widely a word is used, the harder it is to legally protect as a trademark. In a brand name’s infancy, however, the thought of gaining this kind of cultural currency is an inspiration to professional namers, says Alex Frankel in his new book “Wordcraft: The Art of Turning Little Words into Big Business” (Crown, $24.95).