A great star is rarely a great actress. Garbo, Davis, Hepburn—magnificent performers all, but all unwilling (or unable?) to doff their powerful personas and simply be another being. But now, in a sad, funny, wonderful new movie called Terms of Endearment, a 28-year-old American actress gives vivid promise that she may be that special exception: a star who can actually lose herself in the parts she plays.

Her name is Debra Winger, and like many of the great ones she is hardly a beauty. Her eyes are froggy. Her mouth drifts vaguely to the southeast. Her speaking voice sounds like five pounds of walnuts being cracked underwater. Yet like a medium, this young woman can dissolve her boundaries in the wild smoke of imagination and become whoever she wants to be. "She's a metamorphic actress, this girl," says Jack Nicholson, one of her co-stars in Terms. "I think she's a great actress—a genius."

Winger came to stardom in 1980, when she slid aboard a mechanical bronc in Urban Cowboy and stole the show by rocking her bottom and rolling her eyes in a parody of slo-mo masturbation. Next she won an Oscar nomination for brilliantly filling in a blank: the role of Richard Gere's mill-town doxy in An Officer and a Gentleman. Finally in Terms she found a character worthy of her steel.

Winger is cast as Emma, the down-to-earth daughter of a hilariously over-decorated python (Shirley MacLaine) who truly loves her only child but regularly forgets you're not supposed to eat the thing you love. Starting out as a bobby-soxer with a mouth full of braces, Winger winds up about 14 years later as a gray-faced faculty wife shut up in a small college town with three wonderful kids, a limp academic husband who furtively plays back-seat bingo with his favorite coeds—and a cancer that is quietly eating her alive. All the while, she plays cello to her mother's trumpet in a subtle, touching love duet, the year's finest piece of inter-acting; and at every stage of the story she is simply and translucently Emma, inhabiting her character as naturally as red inhabits a rose.

Seemingly effortless, Winger's work is in fact achieved by ferocious effort—she trained for four and a half months to play two small scenes in which Emma is pregnant. "For three months I walked around with pregnancy pads. Every two weeks I added weights. I slept with the pads. My back was killing me. I never gave in."

Winger's drive sets up collisions. She fought continually with Shirley MacLaine, who fought back. At times the air was so thick with verbal missiles that, as director James Brooks remembers wryly, "I got a feeling I wouldn't notice if they threw up on me." Winger insists that "a lot of what was mistaken for tension was two actresses working." Maybe so. But one eyewitness recently remarked: "They'd better split the Best Actress award two ways. Otherwise the loser is gonna brain the winner with a little gold-plated statuette."

Winger has always been recklessly assertive—"wild" is the word she uses. Growing up as a Jewish princess in Cleveland and later in Los Angeles, she was a raving hypochondriac who woke at night and screamed that she had cancer until her parents rushed her to the emergency ward. At 16, she ran off to a kibbutz and did her basic training in the Israeli Army. Back home, she was thrown from a pickup truck and suffered a cerebral hemorrhage that temporarily left her paralyzed on one side and blind in one eye. Lucky to escape with her life, she decided to do something with it: act.

When Winger isn't acting, she is frequently acting up. She scorches the freeways in her BMW and puts plenty of sizzle in her love affairs. Her current hot-and-heavy is Robert Kerrey, the 40-year-old Governor of Nebraska. "I have no plans for marriage," she says, "but he is absolutely someone important in my life." She does have plans to produce her own pictures. Because she wants power? "No. I'm interested in taking power away from them. Then I just want to sit back and become an actress again."