The evidence question
Do Native English Speakers Actually Know All Those C1 and C2 Words?
C1 and C2 vocabulary lists can make advanced English look like a collection of rare words. Here is what CEFR levels actually mean, how native-speaker vocabulary varies, and why even native speakers do not know every advanced English word.
A question worth asking.
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Open a C1 or C2 vocabulary list and English can suddenly look unfamiliar.
You may see an obscure verb, a formal adjective, an academic phrase, or an idiom you have never heard in conversation. Then a reasonable question appears:
Do native English speakers actually know all of this?
The question matters because learners often treat advanced vocabulary lists as if they were inventories of words that every educated native speaker carries in memory.
They are not.
No. Native English speakers do not all know every word, meaning, phrase, or idiom that can appear in C1 and C2 learning resources.
Native-speaker vocabulary varies substantially with age, education, reading, work, interests, and language exposure. Research on American English found a very wide range even among native speakers. At the same time, the CEFR does not define C1 or C2 as a fixed number of words that a person must memorize. Its advanced descriptors focus on having a broad repertoire and using language flexibly, precisely, and appropriately. Council of Europe, CEFR Companion Volume Brysbaert et al., 2016
A word labelled C2 therefore does not mean every native speaker knows this word. It means something much narrower about advanced learner vocabulary within the system that assigned the level.
First, C1 and C2 are proficiency levels, not giant word lists
The Common European Framework of Reference for Languages, or CEFR, describes what a language user can do.
At C1, the global scale describes someone who can understand demanding longer texts, recognize implicit meaning, and use language flexibly and effectively. At C2, it describes someone who can understand virtually everything heard or read and express fine shades of meaning precisely. Council of Europe, CEFR global scale
Its vocabulary descriptors follow the same approach.
For C1, the CEFR describes a broad lexical repertoire that lets the user overcome gaps and choose among several vocabulary options. For C2, it describes a very broad repertoire that includes idiomatic expressions, colloquialisms, and awareness of connotation. Council of Europe, CEFR Companion Volume
Notice what these descriptions do not provide.
They do not say that C1 equals exactly 8,000 words. They do not say that C2 equals 15,000. They do not publish a master checklist that every C2 user must complete.
This is important because many online "C1 word lists" and "C2 word lists" look more absolute than the framework itself.
The English Vocabulary Profile is descriptive, not a list of words every advanced speaker must know
One influential source of CEFR-linked English vocabulary is the English Vocabulary Profile, or EVP.
The project used learner evidence, dictionaries, frequency data, examination corpora, academic vocabulary sources, and large corpora of first-language English to describe vocabulary associated with different learner levels. Its stated approach was based on what learners do know, rather than prescribing everything they should know. Capel, 2012
The distinction becomes especially important at C1 and C2.
The researchers explicitly noted that advanced learners develop vocabulary connected to their own work, study, and interests. That makes an exhaustive C-level list unrealistic. The project instead aimed to describe a useful common core of words, meanings, phrases, phrasal verbs, and idioms.
At the time of the C-level research, the complete A1-to-C2 resource contained about 6,970 headwords but around 15,000 senses and phrases. More than 5,000 senses and phrases were added at the C levels. Capel, 2012
That difference reveals something important about advanced vocabulary: progress is not simply a march toward increasingly rare headwords.
A large part of advanced vocabulary knowledge is learning more of what familiar words can do.
An ordinary word can contain advanced English
Take a common word such as case.
A learner can know one concrete meaning early and encounter a more abstract meaning later. The English Vocabulary Profile was built at the level of meanings and phrases, not only headwords, because one familiar spelling can contain several pieces of lexical knowledge acquired at different stages.
The same problem appears with phrases, collocations, phrasal verbs, idioms, register, and connotation.
So when a learner asks, "Do native speakers know this C2 word?", there may be a hidden second question:
Which meaning or use of the word are we talking about?
A native speaker may use a common word in ways an advanced learner has never met. An advanced learner may also know a technical or academic word that another native speaker rarely encounters.
Both can be true at the same time.
Native speakers themselves have very different vocabulary sizes
A large 2016 study gives a useful sense of the variation.
Brysbaert and colleagues tested native speakers of American English using a large lexical decision-style vocabulary sample. Their estimate for the median 20-year-old was about 42,000 lemmas. But the estimated range was wide: about 27,000 lemmas at the fifth percentile and 52,000 at the ninety-fifth percentile. Brysbaert et al., 2016
The same study estimated that the median 20-year-old knew about 11,100 base words or word families. A median 60-year-old was estimated at about 48,200 lemmas and 13,400 base words. Vocabulary knowledge also differed with education, which the authors linked to differences in reading and study exposure.
These numbers should not be converted directly into CEFR levels. The study measured native-speaker vocabulary under its own definitions, and its threshold for "knowing" a word could be shallow.
But the variation answers our main question clearly.
There is no single native-speaker vocabulary inventory.
27,000 to 52,000 lemmas among 20-year-old native speakers
In the Brysbaert et al. estimates, the lower and upper ends for 20-year-old native speakers differed by roughly 25,000 lemmas. The median estimate was 42,000. Brysbaert et al., 2016
This is not evidence that one group "speaks better English" in every meaningful sense. It shows how strongly a vocabulary total depends on individual exposure and on what the study counts as a known lexical item.
For a fuller explanation of those counting problems, see what an English vocabulary estimate really means.
Why a native speaker can miss a word that an English learner knows
Imagine two people.
One is a native English speaker who works as an electrician and mostly reads news, sports coverage, and technical material related to the job.
The other learned English as a second language and is completing a postgraduate degree in biology.
The learner may know homeostasis, mitochondrial, or epigenetic. The native speaker may not be able to define them accurately.
That is not paradoxical.
Vocabulary grows from exposure. Specialized domains create specialized vocabularies. Advanced learners do not stop acquiring words from their own fields merely because some native speakers have never needed those words.
The reverse is also true. A native speaker may know regional expressions, childhood vocabulary, cultural references, slang, collocations, and ordinary low-frequency words that never appear in the learner's textbooks.
Native vocabulary is broad, but it is not identical from person to person.
Myth: a C2 word is a word every native speaker knows
Myth: If a resource labels a word C2, native speakers should all know it. If they do not, the label must be wrong.
Reality: CEFR-linked vocabulary resources describe advanced learner language. They are not censuses of native-speaker knowledge. At the C levels, even the English Vocabulary Profile acknowledges domain-specific vocabulary and unavoidable omissions. Capel, 2012
A CEFR label is therefore better read as information about when a lexical item or meaning tends to become relevant or evidenced in advanced learner language, under that resource's methodology.
It is not a guarantee about every native speaker.
C2 does not mean "talk like the person with the largest dictionary"
This misconception can distort advanced study.
If C2 meant collecting the rarest possible words, learners could improve simply by memorizing obscure dictionary entries. But the CEFR's vocabulary descriptors emphasize range and control.
At C1, the framework includes the ability to select among vocabulary options and use less common vocabulary appropriately. At C2, it emphasizes consistently correct and appropriate vocabulary use, along with a very broad repertoire and sensitivity to connotation. Council of Europe, CEFR Companion Volume
That makes advanced vocabulary partly a problem of choice.
Knowing commence does not mean you should replace start every time. Knowing a formal synonym does not make the formal synonym appropriate in a text message. Knowing an idiom does not mean it fits every audience.
Advanced vocabulary includes knowing when the ordinary word is the better word.
Be careful with websites that turn CEFR into exact vocabulary totals
Researchers can estimate relationships between vocabulary size and particular language tasks. For example, Paul Nation estimated that roughly 6,000 to 7,000 word families could provide about 98% coverage of some broad spoken-English corpora, while 8,000 to 9,000 could provide similar coverage of written material. Nation, 2006
Those are lexical-coverage estimates. They are useful, but they are not official equations such as "8,000 words = C1."
The CEFR covers listening, reading, spoken and written production, interaction, mediation, grammatical accuracy, phonological control, vocabulary range, vocabulary control, and more. A vocabulary count can describe one part of language knowledge. It cannot certify the whole proficiency level.
The same warning applies to native speakers. A large vocabulary estimate does not turn a person into "C2 plus," and missing an obscure C2-labelled item does not make a native speaker deficient in their own language.
What should an advanced learner do with C1 and C2 vocabulary lists?
Use them as maps, not laws.
A good advanced list can expose you to useful less-frequent meanings, formal vocabulary, academic language, idioms, phrasal verbs, and phrases that your normal input has not yet supplied.
But you do not need to panic because one page contains twenty words you have never seen.
Ask better questions:
- Is this word or meaning common in the English I actually read, hear, or need?
- Is it mainly receptive vocabulary, or will I need to produce it?
- Is it general English or a specialist term?
- Do I understand its register and common combinations, or only its dictionary definition?
- Have I seen it repeatedly enough that learning it now is useful?
Frequency still matters. So does relevance.
If a rare C2-labelled word never appears in your work, reading, conversations, or interests, it may deserve less attention than a common B2 word whose important meanings and collocations you still use poorly.
Native speakers know a lot of English, but not the same English
There is no secret C2 dictionary that every native speaker has memorized.
Native speakers differ widely in vocabulary size. Their knowledge continues to change with age, education, reading, work, hobbies, and other forms of exposure. Advanced learners develop specialized vocabularies for the same reason.
C1 and C2 are better understood as levels of language ability. For vocabulary, the important ideas are breadth, flexibility, precision, idiomatic knowledge, connotation, and appropriate choice. A CEFR-linked vocabulary resource can help describe that development, but it cannot define the vocabulary of every native speaker.
So if you find a C2 word that your native-speaking friend does not know, nothing has gone wrong.
You have found one small example of a much larger fact: people can share a language without sharing every word in it.
Sources and further reading
- Council of Europe — CEFR Companion Volume (2020)
- Council of Europe — CEFR Global Scale
- Capel, A. (2012) — Completing the English Vocabulary Profile: C1 and C2 vocabulary
- Brysbaert, M., Stevens, M., Mandera, P. & Keuleers, E. (2016) — How Many Words Do We Know?
- Nation, I. S. P. (2006) — How Large a Vocabulary Is Needed for Reading and Listening?