TALK TO THE PARENTS of any preschool girl and you’ll find that the word princess doesn’t mean what it once did. It’s been co-opted by the Walt Disney Company.Princess is now a mega-brand, part of a global marketing machine shrewdly designed to accessorize young girls with all the sparkly merchandise their little hearts desire. Worldwide, there are now about 25,000 different Princess dolls, sticker books, pajamas, sleeping bags, toothbrushes, vanity tables, digital cameras, cell phones and multi-level Nintendo videogames. Five years ago, the Princess line generated just $100 million in annual revenue. Next year, it’s projected to hit $3 billion. How did that happen? A decade ago, the marketing of consumer products for Disney characters like Snow White and Cinderella was almost exclusively tied to releases and re-releases of their signature movies. Enter Disney consumer products chief Andy Mooney, who came to the studio from the Nike marketing department five years ago. In a shrewd branding ploy, Mooney bundled Snow White and Cinderella with six of their peers — Ariel, Belle, Jasmine, Mulan, Pocahontas and Sleeping Beauty — and repackaged the whole group as princesses. No longer were these characters identified only with their isolated fairy tales. They were an exalted sorority, a justice league for the sandbox set whose collective popularity was unrivalled by Barbies or Bratz. THE CREATION of the Princess brand was a clever twist on the trend toward line extensions that’s rippled through the consumer products industries in recent years. Robert Hollander, who runs a firm called Brand Sense Partners calls the Princess phenomenon “sub-branding.” “It’s how you segment a brand according to lifestyles,” he told me. Hollander, who brokered a deal with Elizabeth Arden to develop a line of Britney Spears fragrances and cosmetics, notes that the right line extension isn’t just good for sales; it’s good PR. The Elizabeth Arden line, for instance, was introduced at a time when Britney’s public profile was being buffeted by a steady stream of unauthorized paparazzi snapshots. “The way she looks in the advertising is a little more controlled,” Hollander said. But line extensions don’t always work (think New Coke). In their 2000 book “Positioning: The Battle For Your Mind,” Al Reis and Jack Trout call line extensions “a marketing sickness” that “swept through the ad world like Sherman through Georgia.” The more you stretch a product, they wrote, the weaker it becomes. IN DEVISING the Princess line, Disney didn’t just take an existing brand and stretch it. It created an umbrella brand for eight separate characters, giving the whole group a label with the broadest possible connotations. The power of the Princess brand lies in the fact that the meaning of princess is never quite specified. Historically speaking, Pocahontas isn’t exactly a princess (for more on this, see Terrence Malick’s The New World). No matter. By leaving the Princess concept intentionally open-ended, Disney’s merchandising strategy was no longer limited by the narrative minutiae of a particular storyline. It could be adapted to any market condition. Its prospects were limitless. Young girls may grow bored of Pocahontas, but they’ll always want to be princesses. My friends with preschool daughters may complain that the Princess line is a racket. But as rackets go, they find it more palatable than Bratz, a collection of tarty dolls whose trendy outfits are emblazoned with words like “Diva” in rhinestones or glitter. And these days, even Barbie is suffering from an image problem, with Barbie’s Nordic goddess physique far more likely to be found in XXX movies than in real life. The resourceful, hard-working and essentially sexless Disney Princesses don’t have that problem. But perhaps the real power of the Princess brand is to be measured in the way it’s toppled the traditional studio merchandise model, in which toys and dolls begin and end with theatrical product. As studios look beyond box office for revenue growth and shareholder value, they’ll likely become ever more reliant on new content models for their movie characters. Disney is already developing similar branding strategies for its Fairies, Princes and Pirates. Could a Johnny Depp-inspired Captain Jack Sparrow vanity table be far behind?