I came across this interesting question yesterday in a Facebook group about, you guessed it, languages. How many words do you know in your language? My first guess was about 3000, arguing that we need to know about 1500 words to speak a foreign language at a decent level. Hence, I assumed that about twice as many words would be OK for a native speaker.
After some research I have to say that I was quite far off! Taking the example of the vocabulary of a well educated native English speaker we are between 13.000 and 20.000 word families. A word family consists of a base word and its inflected forms and derivations. For example, when you know the meaning of time, you also know timely, timer, time zone etc.
As you can easily see that is more than I estimated but also not that gigantic which makes it an achievable goal for every English learner to acquire about the same vocabulary as of a native English speaker.
A study suggests that an English learner can acquire about 2650 base words per year which means that after six and a half years of learning he or she should have the same vocabulary at their disposal as a native speaker.
Of course, a native English speaker does not have all of his vocabulary at the top of his head all the time. There is a difference between receptive knowledge and productive knowledge. Receptive knowledge means that you understand the word when you hear it on the radio or TV or when you read it in a book or newspaper. Productive knowledge means that you are able to use the word in speaking and writing all the time.
Estimations are that the receptive knowledge is twice as big as the productive knowledge.
In my next article I’ll explain why this is an important point to know for both language learners and teachers.