PRETTY in pink? Not Deborah Watson. “If I see a floral print or pastel dress in my closet, I think: ‘Ugh, gross! I don’t want to wear that,’ ” she said. Ms. Watson, a fashion stylist in New York, has turned her back on those hallowed totems of femininity in favor of the raffish look of a big T-shirt, well-worn jeans and a graying black cotton overcoat. “Anything more girly, I just see as weak,” she said. “It’s not cool to be demure.”

A disdain for such sweetly conventional trappings of sex appeal has trickled down of late from tastemakers like Ms. Watson to scores of followers who are swapping their baby-doll dresses, spindly heels and lace for the flinty attractions of studs and leather, mannish jackets and rock-star jeans. Their embrace of a pointedly aggressive, street-smart style suggests that the more adventurous are rethinking the tenets of female allure.

If the old ideal of sexiness was the shoulder-baring voluptuousness of Scarlett Johansson, the new sexy is the European fashion editor Carine Roitfeld in a black blazer and tall vixenish boots. The look, often slightly disheveled, is shared by off-duty models and style-world insiders.

“We may like Lady Gaga, but in this day and age, women aren’t rushing out to look like her,” said Sam Shahid, the art director behind the provocative advertising campaigns of Abercrombie & Fitch.