Elderhostel. The word has a European flavor to it, and conjures up a wealth of imagery. Elder: old. Hostel: a lodging place for the traveler. Elderhostel: A resting place for the elderly traveler? Hardly.

In five years, Elderhostel, the brainchild of a New England educator and administrator, has come from nothing to a program of learning and travel for the elderly that encompasses college campuses in all 50 states. In 1975 Elderhostel had 30 participants; in 1979 it had more than 12,000 on 235 colleges campuses.

Elderhostel is both a learning experience and an affirmation of an increasingly evident phenomenon already discovered by American business: the graying of America. But its basic premise -- that aging does not dull or warp the intellect or the desire to travel and learn -- needed no slick marketing techniques.

"For senior citizens in the inflation crunch this is a godsend if you don't want to sit on your porch in your rocking chair and feel sorry for yourself," says Frances Grimaldi. Mrs. Grimaldi and her husband, Armand, who live in Wyncote, Pa., a suburb of Philadelphia, discovered Elderhostel last year and they are nothing short of wild about it.

They spent two weeks at Shippensburg State College and Penn State University last summer, and this year, at ages 69 and 72 respectively, they are heading for Sheldon Jackson College, on a 354-acre campus overlooking the Pacific Ocean in Alaska, combining the campus life with a vacation and a visit to relatives.

"We couldn't wait until it started again," said Grimaldi. "We called twice to see where the catalogue was. We were very, very anxious.

The cost of a week on a college campus last year was $95, thanks to foundation and governments grants, and this year it's still that on some campuses, although the national cost has gone to $130. It's cheap when you consider that that includes not only a week's classes, but also dorm rooms, meals and any other campus activities. You can take three different courses in a week, for an hour and a half each daily, taught by the same professors who teach the kids.

A sampling of courses at Shippensburg State this year: Humor in American Society; The Cost of Crime and You; The Symphony: Origins and Development; The American Presidential Election: U.S. Trade Prospects in the 1980s, and Basic Watercolor.

There is only one requirement for the participants: that they be at least 60 years of age, or married to someone who is. For the participating colleges, there is also one requirement -- that none of the courses teach the elderly how to be old.

Martin Knowlton says he was responding to what he saw as two fundamental problems when he started Elderhostel on five New Hampshire campuses in 1975. p

The first, he says, was "the lack of opportunity for older people to see themselves as they really are: intelligent, capable, productive." And the second was more pragmatic -- to attempt to provide a new, ancillary support base for colleges and universities which were using their facilities only 30 percent of the time during the summer.

"I was conscious of and concerned about the particularly evil part of aging that claims as you get older your mind works less well," says Knowlton, who is 60. "It [Elderhostal] really fills a need we thought important by giving you an opportunity to see yourself as a consequential person. Retirement can deny you that opportunity."

Knowlton hit on the Elderhostel idea after returning from a four-year walking tour of Europe in 1974. One of the things that left a lasting impression on him was the popularity of the youth hostel movement there.

Following a long tradition, hostels in Europe provide cheap, dormitory lodging and cafeteria-style meals for travelers. Facilities are shared in a communal fashion while, in addition to costing a lot less, seem to bring travelers closer to one another, and to the country they are visiting.

Knowlton returned to the States impressed with all this and, after toying with various ideas, he hit upon Elderhostel.

"It happened in much greater magnitude than we ever anticipated," he says now. "Once it started it was really uncontainable."

Last year, the Grimaldis took courses in ant and genealogy at Shippensburg, along with a course on sports in American literature, which Grimaldi found especially fascinating because of a lifelong interest in boxing.

Mark Givler, assistant professor of English who taught the course, said his Elderhostel class was the most enthusiastic he'd ever encountered.

"They have more verve than most of the freshmen I meet," he says. "There's no pretension about them; you don't get away with anything. If you're teaching and they have a question, there's no hesitation about asking it."

But it wasn't just the study that thrilled the Grimaldis. It was the experience as a whole. "We're just the kind of people who find living and associating with others fascinating," said Mrs. Grimaldi. "Just meeting other people and sharing their lives and ours. It's a warm, almost a loving atmosphere, even though it's very temporary."

To get a free national catalogue, write Elderhostel, 100 Boylston St., Suite 200, Boston, Mass. 02116. The catalogue contains all details on registration, courses and institutions where you can study. Or you call and ask to be sent a catalogue; the number is 617 -- 426-8056.