The average American knows around 42,000 dictionary words, they say. We've got to do better than that, seeing as we invented them all and all America has contributed is a few random extra Ls to confuse us on the internet.
The research has been published in Frontiers in Psychology, which says that by the age of 20 most Americans can understand the actual meaning of 42,000 words. That seems like a lot, as most Americans on the news seem to only use about 25.
There's a sort of tech angle to it all too to do with machine translation, as lead researcher Professor Marc Brysbaert from Ghent University explains it's all about quickly understanding the shared words: "In Dutch, we have seen that this explains a lot about word processing times. People respond much faster to words known by all people than to words known by 95% of the population, even if the words used with the same frequency. We are convinced that word prevalence will become an important variable in word recognition research."