It used to be that the expert source on what was or wasn't a word was that school-day staple: the dictionary. American Heritage, Webster's Third, the Oxford English: there were a few trusted players in the game.

But what if those players are losing their edge?

Take the word "staycation." Staycation, which means to spend a vacation at home, recently appeared in the New York Times, USA Today and MSNBC. But it isn't likely to appear anytime soon in a dictionary. The same goes for "bracketology," (the science of NCAA March Madness betting) Facebook and Wikipedia.

"We try to cover the most salient" words," says Joe Pickett, executive editor of the American Heritage Dictionary. "What does the educated layperson need to know?"

The people who make dictionaries are known as lexicographers ("authors or editors of a dictionary." Thanks, Merriam-Webster). And they have a time-tested method for choosing which new words to certify and which ones to toss before the next edition or update of a dictionary's Web site.

Groups of editors at a dictionary watch specific subject areas, logging the hits a new word gets. A "hit" is a mention in a book, newspaper or Web site. Then they put the hits in a database and compare the new terms to words they already have. So although Facebook, being a brand name, doesn't qualify, every word in Shakespeare's plays does – including cap-a-pie ("from head to foot") and fardel ("burden"). Being the granddaddy of creative linguistics, Shakespeare invented more than 1,700 words. All of them appear in an unabridged dictionary.

Dictionaries reject words for being too technical (even the most die-hard "Grey's Anatomy" fan will never need to know what a mammosomatotroph is) or for being too young (staycation).

They don't count brand names (Coke, Facebook, Wikipedia) or most foreign words and phrases.

"We aren't trying to be Wikipedia," Pickett said.

So who is? Who's keeping track of, counting and sorting the words English speakers use on an everyday basis?

The Austin, Tex., has been tracking words for the past five years. Using its own teams of experts and its own algorithm, they say English adds a new word every 98 minutes. This means there are more than 900,000 English words in the world, and the one-millionth will appear sometime in April 2009.

In contrast, most standard dictionaries have about 200,000 words, unabridged dictionaries about 600,000.

But the Monitor is so sure of its numbers it has started a Million Word March, a countdown to the one-millionth word.

"We went back to the Middle English and saw that the definition of a word was 'a thought spoken,'" said Paul JJ Payack, president and chief word analyst at the Monitor, "which means if I say a word, and you understand me, it's a real word."

Payack counts staycation, Facebook and Wikipedia as words. But he also follows some of the old rules. For example, words that are both noun and verb, such as "water" are counted only once. He doesn't count all the names there are for chemicals, because there are hundreds of thousands.

Once the Monitor identifies a word, it tracks it over time, watching to see where the word appears. Based on that measurement, they decide if the word has "momentum," basically, whether it's becoming more popular or if it's a one-hit wonder of the linguistic world.

At first glance, this seems a lot like a dictionary's system.

"It's the same as the old [method], just recognizing the new reality," Payack said. The Monitor's method gives a lot more weight to online citations.

But is Payack's "new reality" well, real? He claims that the fast flow of information and the advent of global English have changed the way people use words. And that the gap between the words people use and the words that appear in dictionaries might be on the rise.

"It turns out that once something enters the Internet, it's like an echo chamber," said Payack. Since the first web browser appeared in 1991, the Internet has added a lot of words to the English language—dot-com, blog—and it's added these words fast. The Web has also taken existing words to new ears.

"Back in the mid-'90s, getting a couple of thousand browser hits for a word made us inclined to enter it; now the threshold has changed," Pickett said. "You can find so much evidence for obscure words and expressions."

But dictionaries are used to playing catch-up. After all, it's hard to define a word before it's coined.

Payack says the Internet isn't the most pressing challenge to traditional word-counting methodology. That, in his opinion, is "global English."

English has nearly 400 million native speakers, putting it second in the world, but it has 1.3 billion speakers overall, making it the world's most widely understood language, explains Payack . It's spoken by over 300 million people in India as a second language, and by at least that many second speakers in China.

"Anyone who speaks English right now feels like they own it," Payack says. For example, look at the adjective "brokeback." After director Ang Lee's called his movie about two cowboys who fall in love "Brokeback Mountain," the word "brokeback" wormed its way into the English vernacular as a synonym for 'gay.' Although "brokeback" may be past its glory days in the United States, the word, with this new meaning, is still popular in China, Payack said. It appears on blogs and Web sites, which means it has momentum, which means it's a word.

"Nowadays we have much more human traffic going in all directions around the world," said Salikoko Mufwene, a linguistics professor at the University of Chicago, who has studied the development of regional dialects. Whether or not Chinese-inspired words will become part of American English, for example, "depends on how regularly Americans are going to interact with Asians in English," he said.

And if they did, would Americans become, on average, more verbose? Average Americans use about 7,500 words a day and know about 20,000 total. Even Shakespeare only knew about 60,000.

So the number of words in the English language will always be many, many more than any one person knows or uses.

Both Mufwene and American Heritage's Pickett said English could very well have a million words already. Counting words, after all, is an imprecise science.

It's also not the dictionary's science. The job of dictionaries has always been, Mufwene said, "to reflect how people speak, not to teach them how to speak." If the dictionary reflection grows narrower, it can still be valuable.

"You need people to edit the dictionary and take responsibility for it, so that it's reliable," Pickett said. "And I don't think that's going to change."