The millionth word entered the English language some time ago. This figure includes about 4,00,000 technical terms, the most in any language. Despite the rich vocabulary the Oxford English Dictionary contains, it is doubtful if any individual uses more than 60,000 words. Even those in UK who have undergone full 16 years of education use perhaps 5,000 words in speech and up to 10,000 words in written communication. The membership of International Society for Philosophical Inquiry (no admission for IQs below 148) have an average vocabulary of 36,250 words -- much better than Shakespeare who used about 33,000 words!
Additional reading:
English language (Wikipedia)
