The printed first edition (1755) of Johnson’s A Dictionary of the English Language is huge! The two large folio volumes weigh about 20 pounds. Just moving them from room to room is a workout. Naturally, people want to know how many words Johnson defines in these volumes.
The “how many words” question is notoriously difficult, even impossible, to answer, but every dictionary gets asked about it. Here are responses from Merriam-Webster, Lexico, and Dictionary.com to the question How many words are in the English language? Dictionary.com concludes that the best answer is “more words than you’ll ever use.”
The related question How many words does the average person know? is also tough, because it requires you to figure out what you mean by know. If you see a word you’ve never heard before, but you understand it, does that mean you “know” the word? (e.g., unshoelike, as in the sentence, The latest footwear fashions seem almost unshoelike). What if you are familiar with the word, and you even remember looking the word up, but you can’t quite define it off the top of your head (e.g., iconoclast or paronymous)? If you’re curious about how your own vocabulary measures up, you can get an estimate of your English vocabulary size here and help scientific research as you do it.
You might think that “how many words are in the dictionary” would be an easier question because at least all of the words are written down—but it isn’t! The difficulty lies in defining what a word is. As just one example—should we consider ceiling and cieling to be two different words? (The latter entry says merely “See ceiling.”)
For more examples, and an explanation of how we arrived at our answer of “at least 41,684 words,” see our new FAQ How many words did Johnson define in his 1755 Dictionary?