A million words is just an amazing amount, considering we are born without language at all and learn (primarily through experience and observation) words one at a time. I wonder if there are people who try to learn every word in the English Language, although I don't even really know how you would test that --because every time a dictionary is printed it becomes irrelevant.
A recent CNN article explains which words are considered:
"Words must make sense in at least 60 percent of the world to be official, he said. And they must make sense to different communities of people. A new technology term that's only understood in Silicon Valley wouldn't count as a mainstream word, he said.
His computer models check a total of 5,000 Web sites, dictionaries, scholarly publications and news articles to see how frequently words are used, he said. A word must make 25,000 appearances to be deemed legitimate."
Here's to the one-millionth word in the English Language. Maybe learning them all can be my next project...