"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.