They are called jumpsuits, but they are not for lady leapers. Smartly tailored in elegant fabrics, the one-piece garments can cost $350 or more in boutiques and department stores. Plain or fancy, jumpsuits—actually jumped-up versions of the overalls worn by plumbers, carpenters and garage mechanics—are the hottest A thing going on the U.S. fashion scene these days.
Says Brenda Bird, a buyer for Alexander's, the big New York department store chain: "We can't keep them in stock. Price is no object." Agrees Kal Ruttenstein, a Saks Fifth Avenue vice president: "It's the only...