A "fossil" is something which used to be alive, but has now turned into stone. Dinosaur bones are fossils, for example. The process of turning from a living thing into a rock is called "fossilization".
In language learning, "fossilization" is when a learner' bad speaking or writing habits become permanent and hard to get rid of.
You may have noticed this in yourself. When you first started learning English, you were able to adjust your grammar and pronunciation. Later, it became hard to change your habits, even when a teacher or friend points out mistakes that you're making.
Fossilization is quite common. Even people who have used English for 20 or 30 years usually have bad problems that they can't get rid of.
Causes of language fossilization
There's a common saying in English, "Practice makes perfect." It means that if you keep practicing something, you'll become great at it. There's another saying which is not a popular, but explains why fossilization happens:
Practice makes permanent.
This means that practicing something the right way will help you to improve, but practicing it the wrong way will make your bad habits harder to fix. Most people agree that "un-learning" something is harder than learning it to begin with.
Trying to speak in a foreign language too soon might cause fossilization. This is a controversial opinion. Some language teachers recommend that you not speak in your foreign language until you've been exposed to it for a long time. But other teachers believe that you should try to use the language as much as possible from the beginning.
Hearing and reading too much incorrect English (like when you're in a classroom with other English learners) might also cause fossilization. On the other hand, if you don't study with a teacher, it's hard to get corrections of your mistakes. Lack of corrections is another cause of fossilization.
Of course, attitude plays a big part. You should always:
- try to improve your accuracy
- pay close attention to how English is being used around you
- accept criticism and advice
Common points of fossilization in English
Here are some mistakes that are hard for English speakers to correct:
- Pronunciation, especially of vowel sounds
- Over-using certain words that you learned early on
- Using "a" and "the" incorrectly
- Subject-verb agreement ("he want" instead of "he wants")