How many words are in the English language?

Last week, citing the Oxford English Dictionary, I said that there are 171,476 English words in current use. But after thinking about it, that number seemed awfully low. So I did a little research – and I found estimates all over the place, some as high as a million. It depends on how the “count” is done. The OED counts only “full” entries. Other sources count different versions of the same word (plurals, tenses, spelling), obscure and obsolete words, etc. So the answer to the question “How many words are in the English language?” appears to be: Nobody really knows.