By William G. Connolly
The publication of American Heritage's fourth edition in September 2000 merited both grins and grimaces on copy desks across the land. The grins were no doubt immediate; open the book and you discover a thing of elegant beauty — headwords printed in a subtle, relaxing green and margins alight with photographs, diagrams, maps and drawings, most of them in full color.

The smiles must have grown wider when the rim dug further ino this thoughtful work. Its thousands of definitions — the introduction says this edition has nearly 10,000 new "words and senses" — leave the impression that the editors' aim was to encourage precise but fluid, conversational speech, just the kind that produces literate, reader-friendly journalism.

And there are notes and more notes. Nearly 750 of them discuss groups of synonyms and the nuances of their meanings. More than 400 notes deal with word histories. Some 100 explain regional variations in American language, and more than 50 "Living Language" notes discuss various aspects of nonstandard English.

The notes are fascinating, one and all. But those most likely to be helpful hereabouts are the 500 or so that offer considered explanations and advice on the sort of contentious matters over which copy desks are often riven in the wee hours. Geoffrey Nunberg of Stanford University, a consultant to the dictionary editors, says in an introductory essay that the aim of these usage notes is to provide "the kinds of information that readers will require to resolve questions to their own satisfaction."

Substitute editors for readers in that citation and you'll get the picture. Check, for example, the notes on author as a verb, comprise and compose, contact as a verb, disinterested vs. uninterested, enormity vs. enormousness, flaunt vs. flout, fulsome, fun as an adjective, graffiti and graffito, historic and historical, hopefully and that and which.

Purists might disagree with American Heritage's editors in many cases (host as a verb, masterful vs. masterly, convince and persuade, due to vs. because of, finalize), but in every such instance the dictionary offers a thoughtful note that outlines the issue.

The usage notes, by the way, are based on periodic surveys of a panel of about 200 "respected users and students" of the language. The surveys go back to the 1960s, so the notes can trace the subtle evolution of American English in recent decades. The panel is heavy with authors and academics, but includes about a dozen journalists (Natalie Angier, Molly Ivins, Anthony Lewis, Mary McGrory, William Raspberry, Frank Rich). Though there is nary a copy editor among them, the evidence suggests that most of these "respected users" would pass muster on the rim.

Given all this good news, why should there have been grimaces on the copy desk when American Heritage's Fourth Edition appeared? Because it is not journalism's dictionary of choice and is not likely to attain that status as long as The Associated Press endorses Webster’s New World College Dictionary.

But there may be hope. Webster's New World is now owned by Hungry Minds Inc., which publishes the "For Dummies" books. Someday, when an updated edition of Webster's New World appears under the title "Definitions For Dummies," we may be able to make The AP see the light.

 William G. Connolly was a senior editor at The New York Times, and is co-author of the Times'  stylebook.