Seniority usually means one thing on Capitol Hill: the congressional pecking order. But for about five days each year, the word takes on . . . er . . . some new wrinkles.

"It's in our best interests to remind the folks in Congress that we're alive and kicking," says Ruth Cooper, who at age 65 looks more like a typical grandmother than a budding political activist. She's both.

Cooper is one of 230 older Americans from 43 states who converged on Washington last May for the Senior Citizen Internship Program, an annual opportunity for Congress and the elderly to eyeball each other at close range.

"We came to learn some shortcuts in dealing with the federal government as community activits," says Cooper, whose trip from Louisiana with her husband was sponsored by their U.S. senator, J. Bennett Johnston (D-La.)

"What amazed me is there are so many programs for the aged that I've never heard about," she says. "And if I didn't know . . . well, you can bet as soon as I got home, I started telling others."

Showing older citizens the ropes in community action is the design of this program, the brainstorm of Rep. Elwood "Bud" Hillis (R-Ind.), that started eight years ago with only nine interns.

Since then, 730 seniors have participated. Last year's class was the largest with 150 congressmen volunteering to sponsor persons from their home states and districts.

"The idea is to give them a firsthand view of the federal government and how it operates with regard to the elderly," says Donna Norton, former executive assistant to Rep. Hillis and manager of the program from its beginning.

While in Washington, says Norton, to get to know each other. They also develop a rapport with their congressional sponsors, "planting the seeds of a communications network that'll last longer than 10 days on the Hill."

"We encourage them to make contacts, to make themselves known, and to jot down names and telephone numbers of agency officials responsible for aging programs. "By the time they leave, we want them to know what buttons in the federal bureaucracy to push to get things done for the elderly in their communities."

Along with their armchair advocacy, interns work daily hours in their sponsor's office and attend an exhaustive schedule of discussions on aging issues sponsored by federal agencies, private organizations, and congressional leaders.

Although usually sedate, some workshops have exploded in heated confrontation. Last year, a stunned Housing and Urban Development official was cornered by a dozen irate interns -- all probably twice his age -- demanding straight answers to their questions.

"Ironically, with all the action here, it's when they go home that their intership really begins," says Norton. "This isn't your typical selffulfillment internship. This is a unique program that helps seniors better serve others.

"Once in their hometowns again, they're expected to become liaisons with their congressional offices, keeping us informed on the special needs and problems of the aged while keeping other senior citizens up-to-date on legislation coming out of Washington."

A former Ohio intern returned home to ferret out federal funding for senior transportation serves. A Georgia intern persuaded state officials to bankroll a senior fitness center. A series of newspaper articles by a Florida intern led to a statewide syndicated column on aging.

Morris Rogat, a fiery 66-year-old 1980 intern from Port St. Lucie, Fla., says the program affected him like "political Geritol."

"I'm going to run for the U.S. House of Representatives in 1982," he vows, pointing to his Senior Power" button. "There are more elderly Americans than ever before -- and that means a powerful voting bloc."

When Kenneth and Ruth Rumery, both 63, returned to Davenport, Iowa, they intended to organized local seniors into a political grass-roots movement. t

"We went to Washington so we could learn how to help make living better for others back home," says Ruth Rumery. But before they could start, an organization which sends retired executives abroad for two-month stints in developing countries flew the Rumerys to Costa Rica.

"Instead of helping Davenport senior citizens, we were suddenly unofficial citizens, we were suddenly unofficial representatives of the United States and of our age group in a foreign country. The internship made us better at both."

Most interns target specific issues of the elderly in their own communities.

Cora Wood, for example, an 80-year-old intern from Colmar Manor, Md., (sponsored last year by Rep. Gladys Spellman), is using her contacts and experience as an intern to combat housing shortages for the elderly and poor conditions of nursing homes.

Meanwhile, the elderly of Metarie, La., benefit from Ruth Cooper's efforts to revamp health-care services.

"It's time," she says, "to make health-care services suit the needs of the community rather than the whim of a government official in Baton Rouge or Washington. Seniors got to get off their rockers and work together.And that's the value of the internship program -- teaching old dogs new tricks."