When Washingtonians hear the word "entertainment," they reach for their Trollope. As a television market, the metropolitan area ranks seventh in the nation. The size of the film market is hard to come by, but various estimates place it sixth at the absolute best.

But in book sales, Washington is fifth.

The contrast may be even more dramatic than it sounds. While the television and movie rankings are current, the book statistics are based on 1987 Census figures. Since then, there has been dramatic growth in the Washington market, including four Super Crowns, more than a dozen ordinary Crowns, two large branches of Olsson's at Metro Center and Bethesda, a large new B Dalton Bookseller on K Street, the expansion of several independents, the establishment of Bick's Books, Astraea and Borders and several specialty shops. In the 1987 figures, the two cities placing third and fourth, Boston and Chicago, outsold Washington by less than 15 percent.

There are other ways to rank the data. In terms of bookstore sales per capita, Washington in 1987 ranked seventh. Half of those ahead of it, however, were university towns: Austin, Tex. (No. 1); Madison, Wis. (No. 2); Lansing, Mich. (No. 6). And in terms of bookstores per 10,000 households, it again ranks fifth, but is edged out among large cities only by San Francisco.

"Selling books in Washington is booming and will continue to grow," says William Lofquist, publishing analyst at the Department of Commerce. "Signs are that the area is increasing at a faster rate than elsewhere. We're a rich community that invites a lot of talented people who are avid readers." (Unfortunately, the next round of census data that would confirm this won't be published until 1995.)

If the metro area is a better market than it's sometimes given credit for, it's also atypical. For one thing, there is relatively little down-market selling here, owing to the absence of a blue-collar work force. Borders arrived with a romance section full of titles such as "Sweet Savage Lust," but has found little audience for them. Westerns likewise don't do well here, and neither do blood-and-pulp series such as "The Executioner."

Without a world-class university and resulting student concentration a` la Berkeley or Cambridge, the opposite end of the scale -- call it the avant-garde, modernist or cutting edge -- is also lacking.

"You're talking about a city whose favorite authors are Jane Austen and Anthony Trollope," says John Thomson of Bartleby's. "It's not a town of heavy intellectuals. It's also a town where, more likely than not, the best-selling books will be written by someone who actually lives here."

Often, those books are policy and political tomes. While traveling the country looking for material for his second-hand store, Thomson says, "I never see those books on shelves in used bookstores, which means they weren't sold into those markets."

At Borders, manager Mitchell Stengel says many customers come in looking for specific things. "I wouldn't go to the point of calling them arcane, but the much more unusual and specialized things, like Feynman's 'Lectures on Physics' and the Loeb classics library, move off our shelves as fast as we can put them out."