There is a huge misconception among many language learners. They believe their comprehension troubles are due to a lack of vocabulary. “If I just knew more words, I’d be able to understand more.” In reality, this is rarely the solution.

Korean teachers have long been obsessed with cramming as many words into students’ brains as possible. Weekly vocabulary tests consisting of more than 50 words are not unheard of. Of course, those words start disappearing from memory as soon as the test is over. Visit any bookstore in Korea, and you’ll find a large selection of books promising to increase your English vocabulary.

On the surface, this argument makes sense. You struggle to understand that TV show because you don’t understand the words you hear. Your English-speaking friend uses words you don’t know. But upon closer examination, this argument falls apart. Don’t get me wrong—you can always learn more words. But learning more words is not the solution to your comprehension struggles.

Isn’t learning new words helpful? How much study time should I devote to learning new words?

Though research suggests that we stop learning new words in middle age, this is not the case for everyone. Even as I approach 50, I still learn new English words. When I encounter an unfamiliar word in an article or a book I’m reading, I look it up. Sometimes I’ve heard the term but never fully understood what it meant. Or it could be a brand new word to me. Whatever the case, I’m always happy to increase my vocabulary—when the opportunity arises. It’s not something I strive to do daily.

A picture of random word blocks, to represent vocabulary size

But you should NOT devote hours and hours each week to memorizing new words. Chances are, you’ve already encountered most of the words you need to get by in most conversations. So what’s going wrong? Why do you still struggle to follow discussions and movies?

How many words are there? And how many do I need to know?

These are not simple questions. Without going into too much boring detail, we need to define what a word is. For example, run is a word. What about the past tense, ran? Is that a different word or a different form of run? What about runs, running, and runny?

Without getting too technical, we can use two different terms here—lemma and lexeme. Lemma means the word you’d find in the dictionary. Lexemes are units of meaning. Lexemes can be variations of a lemma but can also include phrasal verbs and idioms. A lemma is always one word, but a lexeme can be one or more words.

A picture of an entry in a dictionary for the word dictionary, to introduce the idea of lemmas

Using dictionary entries (lemma) as a unit of determining words, how many words are there in English? Are there more words in English or Korean?

Again, not easy questions…it depends who you ask!

Interestingly, there are roughly the same number of words in English and Korean. One review of online dictionaries actually lists Korean as the biggest online dictionary (1,100,373 words)—but that is a combination of South and North Korean dialects. The standard Korean Language Dictionary contains 511,282 entries. The English Wiktionary includes 520,000 entries, while Webster’s Third New International Dictionary contains 470,000 entries. It turns out, Korean may actually have more words than English.

Some claim English has over 1 million words. But those estimates include archaic forms no longer in use, as well as lexemes. An often-cited number is 171,476, which is the number of entries in the Oxford English Dictionary. Keep in mind this refers to lemmas, not lexemes. That means we count run, but not runs or ran. We also count running (but not as the continuous form of run) and runny.

How many words do native English speakers know, on average?

How many of those 170,000 words does the average native English speaker know? Again, estimates vary greatly, but most put the number somewhere between 10,000–50,000. Let’s agree that 25,000 is an acceptable rough estimate of typical vocabulary size for a native English speaker. Let’s put that into perspective. The average native English speaker knows about 15% of all the words in English.

A picture of the 15 ball in pool to introduce the stat that most native English speakers only know about 15% of all the words in English

There is still room for confusion, though. Sometimes estimates about vocabulary size refer to words. Other times they refer to word families or lexemes. Knowing 25,000 lemmas is very different than knowing 25,000 lexemes. Going back to our earlier example—run, runs, ran, running, and runny would only count for 3/25,000 lemma, while they would count for 5/25,000 lexemes.

ESL/EFL learners will likely never come anywhere near the vocabulary size of a native English speaker—even after years of study. The nature of how we typically learn words in our native language differs from second language acquisition. But do you need to know as many words as a native speaker? This study suggests that learning 2,000–3,000 word families (lexemes) will allow you to understand 95% of a typical English conversation

A picture of a street address with the number 95, representing the stat that you can achieve 95% comprehension in a conversation knowing the 2,000 most common words

Let’s put that into perspective. According to an answer here (which appears to confuse lemmas and lexemes), learning another 2,000–3,000 words would increase your vocabulary size to 5,000. But that would only give you a 1% gain in comprehension, from 95% → 96%. Do you see why learning more words isn’t the answer? Whether we’re talking about lemmas or lexemes doesn’t matter. It’s the law of diminishing returns. After a certain point, more time and effort spent yields smaller and smaller results. 

Comprehension is not about vocabulary size. It’s about knowing the right words. The words used most often—and as many of the different meanings those common words might have. 

Confident you already know the 2,000 most often used words? Are you sure?

If I asked you, “Do you know what the word have means?” I’m confident you’d say, “Of course!” But do you really know what it means? A couple of weeks ago, I shared a post on my Facebook page that took a humorous look at the different meanings the word ‘have’ has in English. In the video, there are almost 20 different uses of this very common word. My go-to online dictionary,, lists over 15 entries, two phrasal verbs, and 15 idioms related to have. Still confident you know what have means—all the time?

A word cloud in the shape of a runner, using different phrases which include the word run to indicate all the different uses of run

Let’s take the example from earlier—run. Simple word, right? Run is a very basic word we learn early on when learning English. And again, I’m sure you’re confident you know what it means, right? Would you believe that run has over 80 entries in Here are some examples of different ways the word run can be used:

  • run in a race
  • run a business
  • run for office
  • run a fever
  • run into someone
  • have to run
  • runs every hour
  • to be run ragged
  • the engine is running
  • have a good run
  • run up a bill
  • in the long run

I’m assuming you know most of the 25 individual words above. Yet you may struggle to comprehend all the phrases. And that’s why you struggle to follow conversations and TV shows. Learning 10,000 words won’t help you if words like have and run cause you trouble.

You’re telling me to stop learning more words—what should I do?

Do exactly that—stop learning more words! Learning that domicile is a fancy word for home is not going to help you in regular conversations. Focus on the 2,000 most frequently used words. These are lemmas, but you should also concentrate on lexemes. Run appears in this list, but runs, ran, running, and runny don’t. But it’s an excellent place to start.

A vector image of two face profiles facing each other. Each face consists only of the word phrases, introducing the concept that students should learn words in phrases, rather than in isolation

Don’t learn individual words. As explained, lexemes (units of meaning) are often phrases. I’ve always told students to learn words in phrases. This helps you remember what part of speech it is and how it’s used, especially if it’s part of a standard phrase or idiom. It doesn’t help you to learn run on its own in the expression “run for office” or “run for president.” Learn these phrases. That’s how you’ll use run when it means “attempt to be elected for a position.” You’ll also remember that the correct preposition is for.

Another powerful tip is to learn prefixes and suffixes. Once you know the base word (lemma), you can apply the prefixes and suffixes. You’ll expand your vocabulary without having to learn more words. 

Let’s say you know the words appear, allow, connect, and continue. You then learn that “dis~” at the beginning of a verb gives it the opposite meaning. This enables you to understand disappear, disallow, disconnect, and discontinue. You increased your vocabulary by four words, just by learning what “dis~” means. There are many, many more words that start with “dis~” in English. My go-to resource, lists over 3,000. Obviously, many of them are not from the list of the 2,000 most frequently used words. But this clearly demonstrates how learning prefixes and suffixes can greatly expand your vocabulary, with very little effort.

A picture of to small slips of paper with the words legal and illegal on them used to introduce the benefit of learning prefixes and suffixes

Similarly, you can learn that the suffix “~er” can turn a verb into a noun. You can now take teach, drive, and bake and expand your vocabulary with teacher, driver, and baker.

To comprehend English, you must understand idioms—no ifs, ands, or buts

Learn idioms. I always had my university students do idiom presentations each semester. They were instructed to share idioms they encountered in books, TV shows, song lyrics, or when talking to English-speaking friends. Why are idioms so essential? Sure, they’re fun to learn, but you don’t learn them to use them. You learn them to increase your understanding.

As mentioned earlier, comprehension troubles are rarely caused by lacking an extensive vocabulary. Idioms usually consist of simple words, but they have a special meaning as a unit (lexeme). You likely know the words “under / weather / the / feeling / I’m.” But do you know what it means when someone says, “I’m feeling under the weather?” Unless someone has told you or you’ve studied this idiom, it would be tough for you to know it means, “I’m feeling a little sick.

I picture of a dog lying on the beach, looking a little sad. Used to represent the idiom feeling under the weather

To make matters worse, native speakers use idioms unconsciously—all the time. They don’t realize that to a non-native speaker, these common expressions are incomprehensible. 

I often see tourists speaking to Koreans like they’re native English speakers. They get confused when communication breaks down. But if they changed how they were speaking, it would be much easier for non-native English speakers to understand them. And when I started out as a teacher, I was no better.

Embarrassing confessions of an inexperienced, novice EFL teacher

As a first-year teacher, at the end of class, I’d say to my students, “Okay, let’s call it a day.” I was confused when no one moved. I would then say something like, “Class is finished. You can go now,” and then everyone would pack up and leave. It later dawned on me that trying to interpret the expression “call it a day” literally makes no sense. 

Another mistake I made was constantly asking my students, “Am I talking over your heads?” Invariably, some students would look above their heads in a confused fashion. I was attempting to make sure I was speaking at a level my students could understand. But I was using an expression that they didn’t understand. It confused them even further. I was talking over their heads. Epic fail!

A picture of a woman, deep in thought, staring at the heavens, representing the idea of talking over someone's head

Both examples use simple words that my students likely understood individually. But they were unaware that those expressions had hidden, albeit simple, meanings.

So don’t learn more words. Learn more lexemes. Learn more word families. Learn different meanings and uses of words you already know. Learn idioms. Learn slang. It’s not essential for you to use these expressions to show how ‘fluent’ you are. But understanding them will help you understand conversations better. 

And this will allow you to keep the conversation going. No one will think twice if you end a business meeting with, “Okay, we’re finished. See you tomorrow!” instead of saying, “Let’s call it a day.” But people will notice if you don’t respond when someone else says, “Let’s call it a day,” and you don’t move.

Increase your vocabulary—not with new words, but with new meanings for words you know

This week’s blog involved a rather complex topic. There is still some confusion about how many words, lemmas, or lexemes are needed to achieve 95% comprehension. But the exact numbers aren’t important.

What is important is focusing on the most common words and lexemes. This will improve your understanding far more than learning words like apoplectic and conundrum. But if you do come across a term you don’t understand, by all means, look it up. But the majority of your vocabulary study time shouldn’t be spent on learning new words. 

I hope my main points didn’t go over your head. I think now would be a good time to call it a day. Stop learning more words and start learning more meanings and uses of the words you already know.

I’d love for you to share a new meaning of a word, slang expression, or idiom you learned in the comments.

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