DEMOCRATS ARE calling their gains in this month's elections a victory, while Ronald Reagan and some other Republicans are terming the outcome "a wash." The evidence suggests they are both wrong.

The elections were, in fact, a repudiation of the two political parties by millions of people who stayed home because voting for either side was more than they could bear.

To be sure, reports indicate that turnout in the Nov. 2 elections was slightly higher than in either 1974 or 1978, the last two midterm election years. But that isn't saying much. The 1974 and 1978 turnouts were the worst since World War II and among the worst in the 20th century.

This time perhaps 2 in 5 of those eligible voted in gubernatorial and Senate races and fewer in congressional contests, a dismal showing. Turnout at other times has been sharply higher, and in other nations it has routinely been twice as high.

Indeed, pre-election polls by The Washington Post and ABC News show that disenchantment in 1982 created its own electoral phenomenon, a group that might be called "the new nonvoters." Numbering perhaps more than 10 million, these are people who cast ballots in 1978 and in 1980 -- but not this time.

As uncovered in polls in September and October, the new nonvoters tend to believe more than other frustrated citizens that "nothing much changes" regardless of who is elected to high office. They are also more critical of the conduct and motives of public officials.

This massive nonvoting, it should be remembered, came in a year that should have seen a record high turnout. More money than ever -- some $300 million -- was lavished on congressional races alone. There were vexing national problems, with high unemployment only the most prominent.

Some Senate and gubernatorial races were exciting, with well-known candidates at each others' throats. That was the case in New York, New Jersey, Connecticut, Texas, California and a number of other states.

The congressional races, people were told frequently, would determine the nation's direction more than any off-year elections in memory because President Reagan's working majority in the House was on the line.

Reagan himself, with his ability to provoke strong feelings, campaigned heavily. Indeed, many of those who voted did so because of the president, either to support or oppose him.

But most people stayed home.

Traditionally, the failure to vote has been blamed on apathy. A large segment of the citizenry is just not interested in public affairs and does not care about elections. That was doubtless true in 1982, as in the past.

But it won't do to put too much of the blame for modern-day nonvoting on apathy. It simply isn't reasonable to believe that apathy grows as people become better educated, as problems multiply, and as gobs more money is spent on elections.

The new nonvoters are not victims of apathy at all, judging from what they told Post and ABC News interviewers.

More than half said they have voted in all presidential elections since they came of age; 8 in 10 said they have voted in at least most presidential elections. Apathetic citizens, as best the Post-ABC News polls could spot them, would be those who didn't vote in 1978 and had no plans to vote in 1982. Among them, by comparison, only one-quarter said they have voted in most presidential elections.

The new nonvoters come from all walks of life, cutting almost evenly across income groups and the two sexes. They are of the middle class and working class in equal proportions. They tend, however, to be especially numerous among older citizens.

As a group, they are more apt than the rest of the population to see "no difference" between the two major parties and, in the same vein, much less inclined to see "a great deal" of difference between them. They are more likely, as the commonly asked poll question puts it, to see the United States as being "seriously off on the wrong track."

One series of poll questions, posed in September, asked citizens their views on whether most members of Congress care more about their own power than about what is good for the country; whether most members use their public office improperly to make a lot of money, and whether most members make campaign promises they have no intention of fulfilling.

In their answers, all groups were critical of Congress, including people who said they always vote and those who said they never vote. But the new nonvoters were more critical in answer to every question.

Had similar analysis been done with voter polls in 1974 and 1978, the probability is high that there would have been large numbers of new non-voters in those years. Americans are not suddenly coming to turn away from their leaders; the phenomenon is, in President Reagan's phrase, incremental.

To be sure, there were some bright spots in the 1982 turnout.

For the first time, black Americans appear to have voted in proportion to their share of the population. Ten percent of adult Americans are black, and 10 percent of the voters in Election Day exit polls were black.

Labor unions got out their vote as well. People from union households make up just over a quarter of the population but accounted for about 35 percent of the vote on Nov. 2.

But blacks and union workers saw their choices as simple ones. They perceive Reagan's policies as so bad for them that they felt compelled to turn out and to vote for the Democrats. The new nonvoters, on the other hand, were paralyzed: They are sharply critical of Reagan but fail to see the Democrats as offering alternatives.

The high turnout by angry blacks and union members tended to obscure the emergence of these new nonvoters. Had blacks and union members voted only as they had in the past, the overall vote would not have risen slightly -- it would have declined sharply, even from the low points of 1974 and 1978.