Vocabulary size

Vocabulary size is a crucial measure in tracking foreign language acquisition for language learners. Many students and teachers are unclear, however, on the number of words one needs to know to gain even basic facility with a language. This article covers some of the currently available information on the subject from research studies on the vocabulary sizes of native speakers, as well as those of foreign language learners.

Native Speakers' vocabularies

Native speakers' vocabularies vary widely within a language, and are especially dependent on the level of the speaker's education. A 1995 study estimated the vocabulary size of college-educated speakers at about 17,000 word families, and those of first-year college students (high-school educated) at ~ 12,000. [E.B. Zechmeister, A.M. Chronis, W.L. Cull, C.A. D'Anna and N.A. Healy, Growth of a functionally important lexicon, "Journal of Reading Behavior", 1995, 27(2), 201-212]

Foreign Language learners' vocabularies

Foreign language students obviously start knowing close to zero words, but it is not uncommon to learn several thousand words in a few years. Given the difficulty of study, students quickly start asking themselves - how many words "should" I learn, before I can say, read anything? This is a simple question, but the answer depends on a person's goals. If one wants to say and understand "some things" or even "many things" the answer is - not many - maybe 1000-2000 words. But if one needs to understand "most things" then the number is much closer to that for native speakers.

Vocabulary size vs. Comprehension

I.e. - How many words should one learn?

Francis and Kucera [W.N. Francis, and H. Kucera. "Frequency Analysis of English Usage", Houghton Mifflin, Boston, 1982] studied texts totaling one million words and found that if one takes (and learns) the words with the highest frequency, they will quickly know most of the words in a text:

So it looks like knowing the 2000 words with the highest frequency, one would know 80% of the words in those texts. The numbers look even better than this if we want to cover the words we come across in an informally spoken context. Then the 2000 most common words would cover 96% of the vocabulary. [F.J. Schonell, I.G. Meddleton and B.A. Shaw, "A Study of the Oral Vocabulary of Adults", University of Queensland Press, Brisbane, 1956] These numbers should be encouraging to beginning language learners, especially because the numbers in the table are for word lemmas and knowing that many word families would give even higher coverage. But before you start thinking you would learn a language in no time, think how well you would understand a book in your own language where every fifth word was blacked-out! We cannot usually guess meanings from context when that many words are missing. [Liu Na and I.S.P. Nation, Factors affecting guessing vocabulary in context, "RELC Journal", 1985,16, 1, pp. 33-42] We need to understand about 95% of a text [B. Laufer, "What percentage of text-lexis is essential for comprehension?" in C. Lauren and M. Nordman (eds.), "Special Language: From Humans Thinking to Thinking Machines", Multilingual Matters Ltd., Clevedon, 1989.] in order to gain close to full understanding and it looks like one needs to know more than 10,000 words for that. So, now that we know how many words we are aiming for,...

"Which words should one learn?" - Word Lists

Besides the raw number of words, obviously some words are usually more useful than others. Several word lists have been developed, aimed either at providing quick language proficiency, or an effective means of communication to people with limited vocabulary. Starting in 1930 with Charles Kay Ogden who created Basic English - 850 words, there have been other lists: Simplified English - 1000 words, Special English - 1500 words. The General Service List, [Michael West, "A General Service List of English Words", Longman, Green & Co., London, 1953] (2000 high frequency words compiled by Michael West from a 5,000,000 word corpus), has been used to create a number of adapted reading texts for English language learners. It seems then, with 2000 words, one could understand quite a lot of English, and even read a lot of simpler materials without problems. 2000 words? How hard could that be?! Well, remember, it's not just reading and memorizing the words in a list. Often it takes learning the word in a context to really understand its use. In addition, what is easier, listening to someone explain something in a foreign language, or trying to explain it yourself?

Passive vs. Active Vocabulary

This distinction, which makes even a 2000-word list somewhat challenging to master for active use, is the fact that even if we learn a word, it takes a lot of practice and context connections for us to learn it well. A rough grouping of words we understand when we hear them encompasses our "passive" vocabulary, whereas our "active" vocabulary is made up of words that come to our mind immediately when we have to use them in a sentence, as we speak. In this case, we often have to come up with a word in the timeframe of milliseconds, so one has to know it well, often in combinations with other words in phrases, where it is commonly used.

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