On the runways, a return to CONTOURS

HE biggest news in women's ready-to-wear fashion this season is the return of the hourglass figure, the curved-lined silhouette, and the advent of soft-flowing, unstructured lines -- even for the hard-edged hours between 9 and 5, when business women get down to serious business. The slightly fuller figure is in; the gaunt, bony-looking model is out. The feminine look is in; the square, boxy, man's-suit style is out. The Marilyn Monroe, Jane Russell, and Doris Day types are back -- and the vast majority of women, who were never meant to look like Twiggy, can breathe easy once again.

And apparently, the good news is trickling down to Middle America. A recent Mademoiselle magazine cover splashed the message: ``Skinny girls ain't sexy/Those last 5 pounds -- don't lose them, use them.'' The length EMLINES, which have long since broken away from the uniform code, still vary according to cut and design, but tend to be of shorter lengths, especially in the popular body-hugging knits. To offset the shorter hemlines, many designers, such as Oscar de la Renta and Donna Karan, have brought back the elongated jacket that falls mid-thigh and creates a ``long and short'' silhouette. But the long and mid-calf skirts are still very much part of the general look this season, especially in lace dressing and other ``return to romance'' fabrics. Form, fabric, color OVERSIZE sweaters and baggy pants in heavy cottons and knits are being replaced by light, fluid fabrics -- and the queen of the fabrics this season is silk. The bodysuit is still ubiquitous, but this time in cotton jersey, silk, or rayon, instead of wool jersey.

Technologically sophisticated polyester blends that look like silk or cotton or linen but that hold up under heat and wear and tear are also being used by many leading designers.

Peplum dresses, cummerbund waists, puffed sleeves, sleeveless turtlenecks, collarless jackets, midriff blouses, and tucks and pleats -- all drawing their inspiration from the bygone days of Doris and Marilyn -- are definitely in.

Black-and-white, bold stripes, yellow, and pastels are very popular. The brighter, more strident colors of last season have been replaced by more subdued tones and subtle, monochromatic combinations. Europe and America LITTLE is left of the great divide between the great European couturiers and their American counterparts. Leading designers in both continents -- from Italy's Giorgio Armani and France's Sonia Rykiel and Saint Laurent to America's Ralph Lauren and Bill Blass -- are each individual stars that bring their own style, creativity, and aesthetic philosophy to fashion design and who often (but not always) agree on many points.

American designers, for example, are known for their versatility and commitment to practicality. But the American and the European looks often overlap.

Italy is known for the sartorial expertise of designers such as the Fendi sisters, Gianni Versace, and Giorgio Armani. But America's Calvin Klein or Louis Dell'Olio or Anne Klein can also be recognized for their well-constructed, beautifully fitting suits.

More and more, fashion is the universal voice of wearable art, representative of each designer's creativity, not nationality. Women designers FOR the last few seasons, women designers have been moving to the forefront of fashion. In France, Sonia Rykiel has become a strong leader and trendsetter, and many experts liken her influence to Yves Saint Laurent's. In Italy, Mariuccia Mandelli, under the Krizia label, is sending fashion messages felt around the world. In England, Zandra Rhodes, with her often countercurrent and offbeat London styles, continues to influence a large segment of the population.

And in America, Donna Karan, for years co-designer of the Anne Klein line, struck out on her own this year and is already being labeled by some as the strongest influence in fashion today. Fashion politics HE keynote of fashion this season is elegance and subtlety, whether for day or evening. Daywear is soft, easy, and practical. At the office, the preppie look with the bow tie and double-breasted suit (that simulacrum of the male banker) has been replaced by soft-flowing suits, feminine pantsuits, and dresses with jackets.

The philosophy behind this is simply that businesswomen don't have to look like businessmen.

Well-groomed, clean-cut looks are de rigueur, no matter what sex. Terms such as ``conservative,'' ``proper,'' ``dressing rich,'' and ``streamlined'' were heard at every collection.

For evening wear, long, full, opulent gowns, sequined blouses, taffeta skirts, rich paisleys, and antique lace are in. The idea is that day and evening are two very different experiences. For day, you dress sensibly and comfortably and with some degree of color decorum. For evening, you're entitled to look as if you're invited to the White House at least twice a year. Which means that despite the influence of rock videos, the post-punk culture, and singers Madonna and Tina Turner, fashion has voted Republican this year. The message from both continents: ``Less is more -- less fabric, less shoulder pads, less bulk, less color.''

The password is elegance. -- H. N.