“We’re trying to simplify how we tell the story of what we do, and the name represents that,” said Neil Nicoll, president and chief executive of the organization, whose membership peaked in 2007 and has remained flat.

The challenge, Mr. Disend said, is to continue to make consumers and donors aware of the history, tradition and meaning behind the letters. “It’s particularly a danger in the nonprofit space, where the story and awareness of the history and mission is critical when trying to raise money,” he said.

Perhaps aware of that danger, most organizations that adopt abbreviations as names do so only for marketing and branding purposes. Legally, for example, NPR remains National Public Radio. Procter & Gamble, too, is still, for legal purposes, Procter & Gamble, though it has used P&G for branding purposes since 1999.

Conversely, the KFC Corporation is now the legal name of the restaurant chain formerly known as Kentucky Fried Chicken, but the company uses both names in its marketing.

BP, formerly British Petroleum, adopted its initials after acquiring companies including Amoco and ARCO. ARCO itself used to be the Atlantic Richfield Company. The Obama administration’s use of the old name in chiding BP after the recent oil spill in the Gulf of Mexico has annoyed a number of British publications and political leaders.

While the public seems to have no trouble embracing abbreviated names, the news media often remains stubbornly attached to old names. AARP dropped its full name in 1999 and is frustrated that reporters still identify it as “formerly known as the American Association of Retired Persons.”

“Some names die hard,” said Michelle Alvarez, a spokeswoman for AARP, which changed its name in an acknowledgment that more than half of its nearly 40 million members are not retired.