The battle has been joined. Linguist John McWhorter has proclaimed to the others of his race in America that "it's time to stop calling ourselves African-American and start calling ourselves Black."

Jesse Jackson is having none of it. It is he who is largely credited with getting millions of Americans to stop speaking of the descendants of African slaves in the United States as "black" and start calling them "African-American" in the first place. "It puts us in our proper historical context," he said at a 1988 news conference he held to urge the use of the term. In recent weeks, in response to McWhorter's call, he has restated his continuing preference for "African-American."

If McWhorter succeeds in effecting a nomenclature shift, it will be, by my count, about the fifth in living memory, though I'm not quite sure how to count "people of color."

During this period, white men (to cite another, not quite randomly selected, control group) have been continuously known as "white men." There's no "rebranding" campaign in prospect for them, it would seem. That might be a point to keep in mind.

McWhorter argues that American blacks have only the most tenuous of connections to Africa, that their history is more than the story of slavery, and that meanwhile, immigration into the United States from Africa has nearly tripled over the past 15 years.

That last element may be the most important in the discussion, especially in understanding why this is coming up right now. A Chinese person who immigrates to the US and becomes a citizen is a Chinese-American; an Italian who does the same thing is an Italian-American. But an Ethiopian who comes to the US and becomes a citizen is likely to find himself misunderstood, at the very least, if he expects others to consider him "African-American." This is what Abdulaziz Kamus of Silver Spring, Md., an immigrant turned citizen and community activist, has discovered. He attended a meeting about health education for "African-Americans" and found the organizers pointedly uninterested in reaching out to African immigrants in the community.

Last month, Alan Keyes, the Republicans' late entry into the race for the Illinois Senate seat being vacated by Peter Fitzgerald, took on his opponent, rising Democratic star Barack Obama, as not being authentically African-American. Obama's father was Kenyan, but that seems to be a sort of technicality. (One could raise the perhaps more pertinent question whether Keyes is authentically Illinoisan, but this isn't supposed to be a political blog.)

My personal favorite in all this is Teresa Heinz Kerry, wife of Democratic presidential contender, born in Mozambique of Portuguese parents, describing herself as "African-American."

Walt Whitman wrote, "I contain multitudes." We all do. We contain multiple identities: racial, cultural, regional. As an Anglo-Prusso-Celtic-American, I want to tread lightly here. But I have to come down on the side of more terms, not fewer, to describe all these identities. As a wordsmith I welcome the idea of rehabilitating "black," even as I am glad to keep "African-American." Writers are always in the market for more words; headline writers, in particular, are always in the market for synonyms, especially short ones.

We can trust that our language will develop, or borrow, the words it needs. It may be that the McWhorter/Jackson debate has revealed a continuing need in the American English language for a term to refer distinctively to the descendants of slaves. Maybe the new immigrants from Africa have merely demonstrated that "African-American" is not – or is no longer – the right one.

"Express" is a word on the move lately. Clever marketers have given it a whole new lease on life – have you noticed?

The basic idea behind "express" and its many forms is that of "pushing out." "Ex" is a Latin for "out," as in "external" or "export." As a stand-alone word, "press" has a life as both a noun and a verb. It's also an element in any number of longer words, such as impress, compress, depress, repress, and suppress, all of which are tied up with different concepts, physical or metaphorical, of "pushing" in, together, down, back, or under.

"Express" and its variations turn up in some richly emotive and evocative parts of our lives – the adventure of travel, for instance. We "express" feelings and ideas; when people-watching in a café, we make note of a particularly expressive face across the room. We "express" our identities in clothing that is fashionable – or not. And quite a number of clothing stores have "express" in their names, perhaps to suggest both speed and fashion.

We "express" critical documents by courier, for example. Many newspapers, full of important or at least engagingly scandalous information, have the word "express" in their names. (Can't you hear the "thunk" of the bundled papers tossed off the train and landing on the platform?)

Ah, yes, the adventure of travel. The very sound of the word suggests the hiss of a steam engine (never mind that steam trains live on mostly as tourist attractions), and all the glamorous trains one ever dreamed of taking: the Orient Express and its perhaps less glamorous kin.

Connoisseurs of the fine points of campaign-finance law distinguish between express advocacy, which specifically urges people to "vote for" or "vote against" someone, and "issue advocacy," on the other hand.

In all these, the concept of "pushing out," as a kind of "transmitting," is clear. It's even easy to imagine that the express train – or bus or subway – is the one that pushes off at high speed, takes off like a rocket, you might say.

But in a transportation context, the metaphor behind "express" seems to be that of explicit intention: The express train is the one you take when you really mean to get where you're going.

In practical terms, though, an express train is one with limited stops. And this notion of "limited" has led to an interesting adaptation of meaning. Have you noticed how often "express" shows up in product and corporate names to mean "stripped down" or "light"? One of the best examples is Microsoft Outlook, the well-known e-mail and personal information management program, and Outlook Express, its much simpler little brother.

There are "express" versions of certain retailers, for instance, where the customers presumably trade away some breadth of selection for greater convenience of location. If you're just looking for paper clips or a box of file folders, maybe you don't really need an office-supply store the size of an aircraft hangar, the logic goes. And if the store can be somewhat smaller, maybe it can be located someplace more convenient than the Megamall of Greater Exurbia.

Another field in which the "express" concept is familiar is the airlines. Now one would think that the aviation equivalent of an express train would be a long-haul flight. But paradoxically, the airlines with "express" in their names – such as US Airways Express – are not generally flying long hauls but rather puddle-jumps.

You have to admire the marketing finesse involving in getting "express" to morph from meaning "having limited stops," which on a train is a good thing, to meaning "having limited features," which would seem in general not to be a good thing. But sometimes less is more. Not every college sophomore trying to organize his term papers, for example, needs the same level of project management software as the Pentagon. It may be that "express" is the new "lite."

"Perhaps," an inquiring reader writes, with a whiff of hope mixed in with exasperation, "you could tell me when the plural of 'millennium' became 'millenniums' instead of 'millennia'?"

Whose idea is this, anyway? Moreover, she's noted that other Latin-derived nouns (e.g., stadium) form their plurals with "s" rather than "a." Shouldn't they all change at once?

Well, perhaps not. My e-mail pal shouldn't ascribe too much logic to English usage. It's not a matter of Latin grammar. It's that different words work their way into English in different ways, and at different levels. One of the glories of the English language is its richness of synonyms, its range of options up and down the scale of formality. Some words are highfalutin; some are for "just folks," better suited to the kitchen table, say, than to the floor of a legislative chamber. Still other words are more universal, used by a broad range of speakers in just about any context.

"Stadium" is one of these universal words. It's derived from Latin, but it has become a naturalized citizen of the English language. Some ballparks are known as "stadiums," and some as "fields." But no one pulling into a filling station to ask directions to Dodger Stadium in Los Angeles is going to feel he's putting on airs by calling it a "stadium." That's what it's called.

"Millennium," however, is a word that, until the closing years of the 20th century, wasn't much in the public domain; even historians deal more in centuries than in thousand-year spans.

The Monitor's dictionary, Webster's New World College Dictionary, Fourth Edition (the standard dictionary of the Associated Press, by the way), gives "millenniums" as the plural, and it probably causes as much gnashing of newsroom teeth as any other single entry. The assumption here seems to be that those who use the word at all should be expected to know it's Latin, and pluralize accordingly.

But a number of these Latin-derived terms have escaped from the groves of academe and the mills of bureaucracy to join everyday speech: words like "data" and "agenda" and "memorandum" and "media." Once they are out in the real world, their special plurals get banged up a bit. People tend to go with the more familiar "s" plurals – or forget that there ever was a singular.

A task to be done, for instance, is "an agendum," which suggests an ancient Roman with hammer and chisel, carving his to-do list onto a marble tablet that fits into the pocket of his toga. (I get a kick out of imagining what it would have been like as a language of not just sage proverbs and inscriptions on famous buildings, but ordinary conversation – you know, things like, "Honey, I've got to work late tonight. Can you pick up the chariot from the shop?" But I digress.)

In our own day, "agenda," the plural, has become a singular: He has an agenda. To say, "He has agenda," might make "agenda" sound like some kind of geeky new fragrance ("with a body of new vinyl and a strong note of dry-erase marker," they might say in the ads).

Or take "medium" and its proper Latin plural, "media" – two forms of the same word, but they've been traveling in different circles for a while. "Medium" in the sense of "psychic" forms its plural with "s" – just like "stadiums" – which may say something about the broad appeal of séances during the 19th century.

Check out the backstory on "media" – it's even quirkier.The Barnhart Concise Dictionary of Etymology has this to say:

"media n. pl. 1927 (used as a singular), perhaps abstracted from mass media, originally, a technical use in advertising (1923). The form media is the plural of medium in the sense of intermediate agency, means, vehicle, or channel, which is first found in 1605."

As you unpack your new inkjet printer, you'll find that the manual that comes with it uses "media" to mean paper, card stock, or whatever else you try to put into the feeder tray.

When Marshall McLuhan gave the world the idea that "the medium is the message," it was singular. But that institution referred to in the First Amendment as "the press" is now often popularly known as "the media," with a singular verb. (Cue CD track of more gnashing of newsroom teeth.)

Changes in popular usage occur almost unnoticeably over time, like the erosion of a beach. Eventually they make their way into the dictionary - or dictionaries. That's the point at which changes can seem abrupt to careful readers. What happens, quite concretely, is that a new edition of a newspaper's preferred dictionary is delivered to the newsroom, it becomes "official" as of a given date, and the newspaper that wrote of millennia and memoranda on Monday will have millenniums and memorandums on Tuesday.

And so back to Dear Reader's question:

"How is a regular ol' amateur writer like me supposed to keep up with these things?!!"

Alas, you'll have to do it the same way I do: pick a good dictionary and cultivate the habit of looking things up.

But if, in your private correspondence with consenting adults, you choose to use "millennia" as the plural of millennium, well, your secret is safe with me.

I'm just back from a few days in London, pleased to have confirmed that I am not at all – as the saying goes – tired of life. What a relief.

I refuse, by the way, to let the exclusive masculinity of Samuel Johnson's language get in the way of my appreciation of his accomplishments. I choose to interpret his references to "a man" to mean simply "a person" – myself, for example. "Sir," I hope I would say to him if I could, "women are more than half the human race: Get over it. To a degree you would find unfathomable, sir, wordsmithing nowadays is women's work, too."

I spent a few hours walking in the footsteps of another great London wordsmith, Charles Dickens. Dickens knew a thing or two about verbal energy. I've been appreciating more in recent years his vast range, his capacity for combining tragedy and comedy, his social engagement. He was a human intersection of the worlds of law and of letters – the onetime law clerk turned parliamentary reporter turned novelist. The streets I explored – around the Inns of Court, Fleet Street, and the Old Bailey – are what that intersection of law and letters looks like as a neighborhood. This was Dickens's laboratory for the observation of humanity as he followed, wittingly or otherwise, Dr. Johnson's advice to his biographer James Boswell that he explore the "little lanes and courts" of London to discover its "wonderful immensity."

This part of London is also the place where one is reminded of the intersection between the word printed by a press and the Word preached from the pulpit. The Reformation was a religious revolution fueled by a printing revolution. Until it was destroyed during World War II, the area just north of St. Paul's Cathedral was a center of the book trades in London from the late 18th century. Here one remembers that a group of compositors was traditionally known as a "chapel." (A compositor was a typesetter back in the days when that term referred to a person rather than a machine.)

St. Paul's Cathedral survived the Blitz largely intact but much of its immediate neighborhood did not. St. Paul's Churchyard, full of Londoners making it their outdoor parlor on a late summer afternoon, is as lovely a construct of cool stone and green lawn and raking golden sunlight as one is likely to see on this earth. But the postwar reconstruction in the adjacent streets was heavy on concrete and reflected an unfortunate concept of modernity.

That, happily, is now being remedied, albeit slowly. As part of the new construction, the Temple Bar, the ceremonial gateway that once separated the Strand, in the royal City of Westminster, from Fleet Street, in the City of London, is to be moved into the renovated Paternoster Square, adjacent to the cathedral. The announcement imparting this intelligence (posted on a bulletin board) included, alas, a couple of apostrophe errors ("Artists impression of the Temple Bar after it's relocation to Paternoster Square"), which a Punctuation Guerrilla had already corrected with a black marker, thereby sparing me the need to take action myself.

This part of London is where one is particularly conscious of being in the hometown of the English language. St. Paul's Cathedral is proverbially the "Paul" whom "Peter" (the Abbey Church of St. Peter in Westminster, subsequently Westminster Abbey, was robbed to pay: The story is a bit too pat for Merriam-Webster, but the abbey's own website includes it as fact. All right, feelings may still be a bit sore even after a few centuries – but in what other city could the claim even be made?

What's up with "key battleground states"? We don't mean Massachusetts, however important it was as the site of the Battle of Lexington and Concord. We do mean Pennsylvania, though not because it includes Gettysburg.

The locution "key battleground states," for any of you who have completely tuned out of the presidential race, has congealed into a set phrase to refer to those states whose voting this fall is not a foregone conclusion. Not that these 17 or so states thought to be capable of swinging toward either President Bush or Senator Kerry aren't often referred forthrightly to as "swing states." Google News, when I checked the other night, showed the phrase "swing states" being used more than seven times for every one reference to "key battleground states." But I'm surprised that this trinomial term – the verbal equivalent of a semi with two trailers behind it – has caught on to the extent it has.

"Key" is one of those short words beloved of headline writers who press it into service to mean "important" or "critical." (When space is tight, even the word "critical" can seem too long.) But it works best when it retains that sense of "unlocking" something: Key supporters are those who encourage others to get on the bandwagon; key contacts are people who open the doors (sometimes quite literally) to other contacts. "Key" can work in military contexts: Success at Normandy was key to the liberation of Paris, we can sensibly say.But better to call the victory "key" than merely the battle, and better the battle than the battleground.

And by the way, don't we have enough "war" going on around us? Wouldn't it be a good idea to keep the presidential election not only civil but civilian? War is the continuation of politics by other means, as Karl von Clausewitz famously wrote. I would not want to have to explain to him why America seems bent on turning politics into a continuation of war by other means.

The West gets collectively nervous when the Islamic world seems to be too much about jihad. But how often must the American polity seem, to those outside it, to be caught up in military metaphors?

Mourning a missed opportunity for metaphor

Now that the Schlesinger report on the Abu Ghraib prison scandal has come out, I have to register respectful regret that the former Defense secretary and his fellow panelists chose to speak in their report of the need to equip American troops with a "sharp moral compass."

I couldn't agree more with what I'm sure was meant. But an opportunity was missed here to harness the energy of an extended metaphor. Sharp? "Strong" would have been a better choice of words. "Sharp" suggests the other kind of compass, the geometric compass, whose point would penetrate that pulpy lined newsprint we used to write on in school.

Surely the magnetic compass is the one that was meant. To recap what we all know: A compass needle is a magnetized bit of iron that, allowed to swing freely, aligns itself with the earth's magnetic field and points north. It actually points to magnetic north, rather than absolutely true north, but it still gets close enough to true to make the magnetic compass one of the key (that word again!) instruments of human history, making possible the great voyages of discovery.

Could we ask for a better, more hopeful, metaphor than this? Yes, the needle trembles a bit when the compass is whipped out of the pocket by the excited or nervous scout who fears he is lost, or wants a reality check against the map. But it soon settles down.

And so it is with our moral decisions. Sometimes the issues are complex and take time to think through. But then the right answer comes as we seek to align our behavior in the moment with our highest sense of principle. As the Scout compass of youth helped us find our way out of the literal dark woods, so a strong moral compass helps us through the dark woods of the challenges we face as adults – even something as grave as Abu Ghraib.