There's a myth about singles life in Washington that dates back at least to World War II and is repeated and discussed by disappointed women in dark moments in dark bars: Single women, they say, outnumber eligible men here by a factor of three, or four or even five to one.

The myth is used by women to explain why they put up with men who cancel dates in favor of doing their laundry, whose only idea of a good time is a beer and the Bullets and who take them to parties and leave them to curdle by the cheese dip.

According to the 1980 census (the most recent figures available), for every 100 single women in the D.C. metropolitan area, there are 81.1 single men. In whole numbers this means that out of 2.4 million adults there are 589,297 single women here, compared with 477,983 single men.

However, the 81.1 figure for D.C. compares almost exactly with the U.S. figure -- 81.3. And among the principal reasons for the imbalance, at least nationally, is simply that women live longer and men tend to remarry more often and more quickly than women.

"There's no statistical basis for the myth about D.C.," says Cynthia Taeuber, a demographer at the Census Bureau here. "It certainly doesn't show in the data."

Looking at the single men/single women ratio by age, the Census Bureau arrives at this breakdown (the figure in parentheses is the national figure):

For ages 20-24, D.C. has 107 (127) single men for every 100 women.

Ages 25-29, 108 (123) single men for every 100 single women.

Ages 30-34, 96 (102) single men for every 100 single women.

Ages 35-39, 89 (85) single men for every 100 single women.

Ages 40-44, 76 (76) single men for every 100 single women.

(Nationally, there are many more single men than single women in the 20-24 age range because women tend to marry men who are a few years older than themselves. Hence the men in the 20-24 bracket are marrying women who are under 20; while the women in that bracket are often marrying men in the next older bracket.)

More refinements of the picture are supplied by Charles Westoff, director of the Office of Population Research at Princeton University. In a study of the U.S. marriage market, Westoff calculated the number of eligible men and women -- defined as those who are single, widowed, divorced and separated, with additional adjustments (not made by the Census Bureau) for such people as homosexuals and confirmed singles -- those considered unlikely to marry.

In Westoff's ranking of the top 38 metropolitan areas, Washington came in eighth, with 66.5 eligible men for every 100 eligible women between the ages of 20 and 59. Most favorable for women was San Diego, with 75.1 men; worst was Nassau-Suffolk counties in New York, with 49.2.

Cities in the South and West generally had more eligible men than Snow Belt ones, due to the migration of single men to these areas in the '70s.

Breaking the figures down into age groups, Westoff came up with the following scale: for ages 20-24, there are 130 eligible men in Washington for every 100 eligible women, the only point where men outnumber the women. For 25-29, the ratio is 97; for 30-34, 82; for 35-39, 62; 40-44, 48; 45-49, 42; 50-54, 38; 55-59, 33.

"Washington is no worse for singles than most other major cities," says Westoff. "It's better than the myth would have it. There's no demographic reason for the myth," although he adds that there may be sociological reasons for it.

One theory, not specifically mentioned by Westoff, is that D.C. is filled with career-minded workaholics -- a condition that makes it harder for couples to meet.

"The problem for adult single working women in Washington is not Washington, it's being an adult single working woman," says Stephanie Faul, 35, a D.C. advertising copywriter and cofounder of the International Society of Thornbacks.

"You're not in college anymore. You don't meet 60 new men every time you go to a new class. The problem is circumstantial -- there's no central directory here. The patterns of your life build themselves into a situation where you don't meet new men, and you also get more selective."

The Thornbacks get their name from an obsolete word for old maids. Started as a tongue-in-cheek operation, the society's membership totals around 100, and believes that it's perfectly okay to be by yourself. "Adult single people have to build their own support groups -- when you are single, you have to rely on each other. The society is, in a sense, our support group."

As for the myth, "It's a hardy perennial," Faul says. "It's always nice to blame someone outside yourself." Keeping the Faith

"Jewish parents and the Jewish community want and expect that their children will marry fellow Jews," says Rabbi Stephen Listfield, "and I think that Jews would prefer to marry other Jews. But we are a minority, and it's hard to meet someone of the same faith."

Listfield, 39, will lecture March 14 on "How to Be Single and Jewish in Washington . . . and Not Have Your Mother Worry." The talk is sponsored by First Class, a new adult learning center. Meanwhile, at his Adas Israel synagogue, he directs one of Washington's larger on-going programs for singles.

"The synagogue stands for tradition," says Listfield. "I'm not a maitre d' or a social director. These aren't volleyball games. These are religious studies and serious lecture groups."

For more information on the seminar, call First Class at (202) 797-5102. For the Adas Israel Singles Newsline: (202) 362-6295. Bartenders' Night Out

Singles bars may have a bad reputation, but bartenders are generally exempted from the disparagement. They're quick, companionable if you're lonely, knowledgeable and above the fray -- or so authorities from Billy Joel to the sitcom "Cheers" to the film "Choose Me" would have you believe.

Such reasoning may help account for the popularity of the annual Bartenders' Ball, the seventh of which takes place Saturday, March 9, at the Washington Hilton. The ball, a benefit sponsored by the local restaurant community, is expected to draw 2,500 people and raise over $80,000 for Washington-area charities. For more information: (202) 628-3234.