A couple of marketing professors set out not long ago to define frugality. It seems that thrift is so alien a concept to the average merchandiser that the authors had to make it sound profound for it to sound real.

"Frugality is a unidimensional consumer lifestyle trait characterized by the degree to which consumers are both restrained in acquiring and in resourcefully using economic goods and services to achieve longer-term goals," wrote John L. Lastovicka and Lance A. Bettencourt in a recent Journal of Consumer Research.

In other words, as your grandmother might say: "Use it up, wear it out, make it do or do without."

But your grandmother probably cared more about frugality, and knew better what it was, than anyone you know now. In fact, Lastovicka and Bettencourt found that only 10 to 15 percent of the population is frugal. "We're living in the lap of materialism," says Lastovicka. "What makes a lot of our current culture go is buying and investing. . . . If you go back in our country's history, frugality was dominant. And now it isn't."

The authors did not differentiate among the genetically frugal, the ecologically frugal and the unwillingly frugal. Nor did they distinguish between being frugal--a tarnished but still unassailable virtue--and being cheap, which is not admired by anyone but Scrooge McDuck.

Despite their six studies and 64 reference works ranging from John Stuart Mill to the Tightwad Gazette, clearly Lastovicka and Bettencourt (professors at Arizona State and Indiana University, respectively) need a little help.

First of all, they were hampered by the constraints of the scientific method, which requires that you come up with a unique idea that has to be verified, and that you use the word "nomological" as often as possible. But in this season of excessive non-frugality, it behooves us to take this subject as seriously as Lastovicka and Bettencourt have, but expand the canvas, as it were, to include monomaniacal as well as nomological considerations.

Let's take a common situation that occurs between a frugal spouse and a cheap spouse. The frugal spouse does not fill the gas tank of the family car until it is empty, which is a more efficient use of time, she thinks. But then she finds herself with the gas gauge at totally empty, possibly even fumes, and her sweetie is at the wheel. He passes the first gas station. "$1.31 a gallon!" he says. "But . . ." she says. Then he ignores $1.29, and $1.28. Finally, just when she is about to have a nervous breakdown because they are going to run out of gas on the 14th Street Bridge and die, he spies $1.27 and slides into the bay with a satisfied smile.

This is a cheap person, because he is willing to risk life and limb for less than 50 cents.

Some people think they are frugal until they meet the real pros. "I am convinced it's a gene," says Bette Land, a Tenleytown frugal who buys everything on sale, has joined the D.C. Film Society to get movie deals and lives with an eco-frugal son, Andrew. (At 24, Andrew is living at home to save money, of course, so he can travel and see the world.)

But Land can be quickly outgunned. "Do you reuse your Ziploc plastic bags by washing them?" she is asked.

"WHAAT?" Land says. "I've never heard of that."

"Oh yes. And some people sew them up when they start to rip."

"Oh, God," she says. She tries to recoup. "I do reuse shopping bags."

Perhaps it's time to refine the definitions, especially for the academics and the nomologically challenged.

Frugal is buying a dress on sale.

Eco-frugal is buying a dress made of natural fiber grown without pesticides, on sale--only if there is no harm done to peasants in Guatemala in the process.

Cheap is buying a dress, wearing it once, and returning it to the store for a refund.

Frugal is buying the cheapest paper towels because basically they are all the same, or not buying them at all.

Eco-frugal is not using paper towels and using cloth instead.

Cheap is drying out paper towels and reusing them.

"Frugal people are a little more rational," said Lastovicka. He rides his bike to work, 40 minutes each way. He sees himself as frugal, bordering on eco-frugal. "Cheapness can reflect a social insensitivity to others."

Frugal people, however, seem to have many enviable traits. In studies conducted at their respective universities and in airport waiting lounges, Lastovicka et al. found that tightwads are less likely to be influenced by peer pressure, are careful with their possessions, are not always "coupon-prone" and tend to be goal-oriented.

They also found that a husband's evaluation of his wife's frugality tends to differ from her appraisal of herself and vice versa. (They had to study this?) Other studies by Freudians have found that frugal people tend to have orderly and anal personalities and be somewhat more authoritarian.

Frugal is not eating in restaurants.

Eco-frugal is eating only in restaurants that serve pesticide-free food and recycle leftovers to soup kitchens.

Cheap is eating in a restaurant but tipping only 5 percent, and stealing the sugar packets when you leave. You've seen those people; they are shameless.

"Here you have somebody working as a waiter for less than minimum wage," says Lastovicka. "Your savings is at someone else's expense. Cheap suggests that you may be harming your relationships with other people."

Here is a test: You are walking along and see that some spendthrift idiot has thrown out a new set of bath towels still wrapped in plastic. They are an unfortunate shade of orange. You (a) take them home and use them for 16 years; (b) wrap them up and give them to your brother for Christmas.

If you answered (a) you are both frugal and eco-frugal. If you answered (b) you are cheap.

The lexicon of cheap is not attractive. "Shoddy or inferior . . . mean or contemptible: a cheap joke . . . of little account or value . . . stingy; miserly," says the Random House Dictionary. These people are sour, dry, the Mr. Bumbles of the world, denying soup to Oliver Twists. They are as stingy with their emotions as they are with their pennies.

Frugal, on the other hand, connotes an element of saintliness. "Prudently saving or sparing; not wasteful." Every major religion inveighs against acquisitiveness, greed and materialism. "Lay not up for yourself treasures on earth," says the Bible. "The person who lives completely free from desires, without longing . . . attains peace," says the Bhagavad-Gita. Laws against excessive consumption were passed by the Puritans and Quakers of pre-Revolutionary Massachusetts and Pennsylvania.

The prevailing view then was that "a man was but the steward of the possessions he accumulated. If he indulged himself in luxurious living, he would have that much less with which to support church and society. If he needlessly consumed his substance, either from carelessness or from sensuality, he failed to honor the God who furnished him with it," wrote Edmund S. Morgan in the William and Mary Quarterly.

Yet it seems that scriptural injunctions about wealth are obeyed even less than the ones about loving your brother as yourself. Long ago some people started to make money selling tobacco and so forth, and they wanted to spend it, and then other people were envious and got into debt trying to keep up, and pretty soon the template of the American economy had been set. Export, import, buy, sell, dig a landfill.

The Depression boosted the cause of frugality considerably, perhaps the only time since Mayflower days that it was the dominant lifestyle. The acquisitive '80s sent the frugals underground, but they proudly reemerged in the early '90s with such publications as Amy Dacyczyn's Tightwad Gazette, which had as one goal "to gain recognition for tightwads as a minority" (as well as "to provide an income for the author, who doesn't want to go out and get a real job"). Possibly the resurgence was fueled by all that credit card debt accumulated in the '80s and the sudden, universal realization that four years of college tuition would soon cost more than Apollo 13.

Dacyczyn's thesis was that if you saved the pennies you could get something you really wanted, like a house, or a spaceship. She--and others, like the Cheapskate Monthly--circulated tips such as cutting whole milk with the powdered stuff, making your own baby wipes, or creating a dryer for those washed Ziploc bags out of an old coat hanger. (One of her readers calculated that washing a baggie took six seconds and saved 5 cents, for a savings rate of $30 an hour.) These people, for whom frugality is a "sport and fun," are now all over the Web.

It took the eco-frugals to bring back the moral element, to remind us that "if everyone on Earth consumed like the average American, we'll need four more planets to hold all the stuff," reports Betsy Taylor, executive director of the Center for the New American Dream, an organization devoted to "responsible consuming." Not only that, 150 million personal computers, made of toxic, undegradable plastic, will be dumped in landfills by 2005. And those little storage rental units you see all over the place are one of the fastest-growing businesses today, she says. There is more spent on advertising in this country every year than the entire budgets of several sub-Saharan countries.

Taylor herself is an example of an eco-frugal. She takes six canvas bags to the grocery in lieu of either plastic or paper, but she buys organic food, which is more expensive.

Taylor says we are at the dawn of a 50-year cycle in which people are going to retrench, recycle and reuse. They want simpler lives, and less stuff. In her vision of the future, it will be possible to get your VCR fixed for less than the cost of a new one, and there will be tax incentives for consuming less.

She is thinking of people like Winifred Roberts, a Takoma Park woman who traded in a high-paying job as a corporate tax attorney 10 years ago for a more relaxed freelance life at one-third the income. Roberts is frugal by heritage, necessity and philosophy. She read the Tightwad Gazette (now available only in book form) cover to cover. "I'd wanted to reuse my foil for years, but I thought it was too weird. Now I feel free to do it. I haven't bought a plastic bag for five years. . . . I don't use a clothes dryer."

She started using her dishwasher for storage after she discovered that it used more hot water than two long showers. And she founded a neighborhood "clutter clinic" that meets about four times a year. People bring stuff they aren't using anymore and if someone needs it, he can have it.

"I just gave away a beautiful all-suede cape I'd almost never worn," Roberts says. "It's been sitting in my closet for 30 years. This young woman looked really nice in it, so I gave it to her. Someone else brought some fresh herbs, and I took those."

Katja Richards, a commercial sales representative for Cort rental furniture, is a new convert. About 18 months ago she took a course in simpler living offered by Fairfax County Adult Education and cut her spending in half--"just by paying attention to what I'm doing." When she sees something she wants to buy, for example, she puts it on layaway; after a week, she usually finds she doesn't really need it.

She has a ways to go, however. Her commute from her town house in Chantilly to her job in Alexandria consumes 12 to 15 hours a week. Her attempt to get by with one car bit the dust when the weather got colder and her husband stopped enjoying his walk to work. But she told her family she did not want any presents this Christmas unless it was the gift of their time, and she placed a $50-per-person spending limit on them.

"I got fed up with the whole environment in the Washington area," she says. "Work, work, work. Everything to make a buck. I was sitting in a traffic backup on I-66, and it just kind of hit me. It's just not worth it."

CAPTION: During the Depression in the 1930s, bread lines and radical frugality were essential for survival. Today, shopping the shelves (and elsewhere) for the best possible deal is "sport and fun."