Unlike most other defeated presidential candidates over the past 25 years, Democratic standard-bearer Walter F. Mondale will not have to give the nation a sample of traditional grace or true grit at his opponent's inauguration.

He has, in fact, decided to hide out.

"He is not going to be in the city. He is not going to participate. That is as much as he wants known," said Patricia Sarcone, Mondale's executive assistant at the Washington offices of Winston & Strawn, the Chicago-based law firm that hired him shortly after he left the vice presidency in 1981 and where he now has returned.

George McGovern was napping in London during Richard M. Nixon's second inauguration in 1973, and Barry Goldwater flew out of Washington the day before Lyndon B. Johnson was sworn in for his one full term in 1965.

But the other recent losing candidates have had to sit on the inaugural platform behind the men who had defeated them, masking any bitterness and pain they felt in a spirit of ceremonial harmony, because of their status as outgoing presidents or vice presidents.

This time, two of last year's presidential aspirants -- Sens. John Glenn (D-Ohio) and Ernest Hollings (D-S.C.) -- are expected to watch President Reagan's second inauguration from the platform with other officials and dignitaries.

The Rev. Jesse L. Jackson, also unsuccessful in an attempt for the nomination, will participate in inaugural functions in a different way. He plans to lead an anti-Reagan march and prayer vigil today and may continue the protest in Washington on inauguration day.

Four years ago, the ill-starred Jimmy Carter, whom Mondale served as vice president, suffered under double defeat at Ronald Reagan's first inauguration, and his overwhelming exhaustion showed.

Carter had hoped that in the final hours of his presidency he could welcome to freedom the 52 Americans held hostage in Iran, ending the national ordeal that had become both his obsession and his downfall. But he was robbed of that personal victory when the hostages remained on a runway in Tehran until five minutes after Reagan had finished his inaugural address.

In that speech, Reagan had thanked Carter for his "gracious cooperation in the transition process," and later asked Carter to greet the hostages in Germany.

At his own inaugural in 1977, Carter had opened his address with a special word for the man he had defeated the previous November.

"I want to thank my predecessor for all he has done to heal our land," Carter had said of Gerald R. Ford.

Ford, sitting on the platform, bit his lip to hold back tears as the audience applauded. Ford later described the touching moment as the most difficult in his day of transition to private citizen.

Like Carter, Nixon played both roles of victor and vanquished on an inaugural platform.

After his narrow defeat to John F. Kennedy, outgoing vice president Nixon put a broad smile on his face as he came down the Capitol steps before the 1961 ceremonies began and was among the first to congratulate Kennedy after his swearing-in.

Eight years later, Nixon was the one giving the inaugural address, and on the platform with outgoing President Johnson was outgoing vice president Hubert H. Humphrey. Narrowly defeated during the height of the Vietnam War -- which then bore LBJ's mark but which soon enough would bear Nixon's -- Humphrey fought hard to look stoical.

McGovern, who had just suffered a crushing defeat, got off lighter at the second Nixon inaugural.

"I was having a nap," he replied with a grin when asked what he was doing while Nixon took the presidential oath. McGovern was in London, where he hosted a lunch for British newspaper executives and attended the ballet.

This year McGovern, who again made an attempt at the Democratic nomination, will teach a regularly scheduled class at Duke University inauguration night, said an aide at his Washington office of Americans for Common Sense.

Sen. Gary Hart (D-Colo.), another Democratic hopeful, will be giving a speech on nuclear arms control and an agenda for the 21st Century at the University of Geneva graduate school of economics and science, a spokeswoman said.

Mondale is concentrating on his law firm work now, Sarcone said. On the day after his defeat, Mondale said he has no plans to seek the presidency or any other elective office.

Geraldine Ferraro, who made history as the first woman vice presidential candidate on a major party ticket, has signed a $1 million contract with Bantam Books for her memoirs. She, too, is declining inauguration interviews.

Ferraro will lunch inauguration day with New York Mayor Ed Koch and spend the evening at home with her family, said an aide.

"What's she supposed to do?" the aide asked. "Celebrate?"