The most recent study on vocabulary size suggests that, on average, people learn a thousand new words per year for their first 15 years and then level off. The authors of Measuring Native-Speaker Vocabulary Size give this formula for establishing how many words the average teenager knows: Take the age, minus two, and multiply by 1,000. “For the vast majority of native speakers,” write I. S. P. Nation and Averil Coxhead, “their vocabulary size will be within plus or minus 1,000 words of this average figure. A very small number will be outside this range.” After the age of 15, vocabulary growth slows considerably unless the person pursues higher education or engages in other activities that enhance word knowledge.

Having an outsized vocabulary correlates with a rich set of life experiences, such as travel and engagement with many different people, together with reading. Having an impoverished vocabulary correlates with low socioeconomic status, infrequent reading, and limited access to technology.

In the mid 20th century, vocabulary-building books suggested that improving your vocabulary was a major key to success in life — even financial success. Enhancing your word stock was part of the self-improvement movement. Many IQ tests depended on vocabulary size as a key element in measuring intelligence. Some still do.

Modern researchers have tended to emphasize that a large vocabulary enhances reading comprehension: The more words you know, the more readily you can understand anything you happen to be reading — whether it’s a newspaper or a sesquipedalian essay.

Like many other commentators, I recommend that people keep vocabulary notebooks. Whenever you encounter a word whose meaning you’re not quite sure of, jot it down — or perhaps take a screenshot — and then record it, together with its major senses, in a notebook. I recommend keeping the notebook in your own hand and reviewing it from time to time. It’s a learning exercise, and you’ll be especially pleased when you read something that uses one of your new words. If you’re an avid reader, that will happen with some frequency.

Enough preliminaries. Let’s have a quiz. The following words appear on bands 2–4 in the Oxford English Dictionary’s assessment of word frequency, meaning they’re not common, but they’re not impossibly rare. (The OED’s online third edition has eight bands to indicate word frequency, from one [rare] to eight [exceedingly common].) All these words have appeared in recent books and articles, and all but two of them can be found in the eleventh edition of Merriam-Webster’s Collegiate Dictionary. On a separate sheet of paper, commit yourself to answers before checking the key.

1. descry /de-skrī/, vb. (a) to criticize, (b) to regret, (c) to portray, (d) to perceive.

2. fetor /feet-uhr/, n. (a) grand feast, (b) stench, (c) arthritis in the feet, (d) the condition of one’s health.

3. florilegium /flor-i-lee-jee-uhm/, n. (a) anthology, (b) gut bacteria, (c) a set of prophecies, (d) fortune-telling by shaking sticks.

4. footling, adj. (a) low to the ground, (b) trivial, (c) involving podiatry, (d) involving pedals.

5. funambulism /fyoo-nam-byuh-liz-uhm/, n. (a) trickery, (b) overheated rhetoric, (c) tightrope-walking, (d) deception by a fiduciary.

6. gibbous /jib-uhs/, adj. (a) moonlit, (b) protruding, (c) involving gallows, (d) characterized by meaningless talk.

7. hamartia /ha-mahr-tee-uh/, n. (a) redirection of libidinal energy, (b) divination, (c) tragic flaw, (d) fear of new ideas.

8. incondite /in-kon-dit/, adj. (a) not credible, (b) unwritten, (c) included within a text, (d) crudely put together.

9. nodus /noh-duhs/, n. (a) the center of attention, (b) a dent, (c) a complication or difficulty, (d) a misappropriation.

10. polysemous /pol-ee-see-muhs/, adj. (a) having many meanings, (b) having more than two legs, (c) involving an intersection with many traffic signals, (d) involving a forest with mostly deciduous trees.

11. sederunt /se-deer-uhnt/, n. (a) an idle person, (b) a grouping of seven, (c) an impertinent remark, (d) a long sitting.

12. stertor /stuhr-tuhr/, n. (a) whispering, (b) lisping, (c) snoring, (d) coughing.

13. stramineous /struh-min-ee-uhs/, adj. (a) scurrilous, (b) strawlike, (c) filthy, (d) strident.

14. tenebrous /ten-i-bruhs/, adj. (a) measured by decades, (b) involving tympani, (c) murky, (d) uncomplimentary.

15. verecund /ver-i-kuhnd/, adj. (a) shy, (b) wizened, (c) down-to-earth, (d) unfailingly honest.

Which two words aren’t to be found in the Merriam-Webster abridged dictionary? The last and the antepenultimate: nos. 13 and 15. They’re both in the OED’s second band of frequency.

If you knew at least half the words, congratulations. You’re a bona fide vocabularian. If you knew fewer, and you wish you’d done better, you’re well on your way. Start your notebook with the words you missed, and commit to adding three to five new words each day.

Next time, in part II, we’ll have another quiz — five-letter words that might be used in a highbrow version of Wordle.

Key: 1. (d). 2. (b). 3. (a). 4. (b). 5. (c). 6. (b). 7. (c). 8. (d). 9. (c). 10. (a). 11. (d). 12. (c). 13. (b). 14. (c). 15. (a).