An average 20-year-old American knows 42,000 words, depending on how you count them

How many words do you know? As Bill Clinton might say, it depends on how you define the word “word.” A new study suggests that—if you’re excluding proper nouns, multiword phrases (like “kick the bucket”), and derived words (like “helplessly,” from “help”)—the typical English-speaking American knows about 42,000 of these so-called “lemmas” by the age of 20, UPI reports. The study, published this week in Frontiers in Psychology , asked more than 220,000 people to review a list of 100 words—some real and some made up—to decide which were actual entries in the dictionary. High scorers—those in the top 5%—knew an average of 52,000 lemmas, whereas low scorers—those in the bottom 5%—knew an average of 27,000. If you want to see where you fall on that scale, you can take the online test here.