3 EFL Terms You Should Know: Interlanguage, Interference, and Fossilisation

Join a global community of over 100,000 TEFL teachers working throughout the world! Enrol me!

If you’re not a TEFL teacher, you probably don’t know what cognates, collocations, or clozes are, or inflection, inversion or IELTS, or minimal pairs, morphemes, or modal verbs – and that’s okay. As with any career, there is a fair amount of jargon related to teaching English as a Foreign Language. If you are a TEFL teacher, in order for you to be on top of your game, it’s necessary for you to be aware of this jargon and to have a solid understanding of the related key concepts of TEFL. But don’t be overwhelmed, we’re here to help!

While it would be total overload to try to tackle all this language in one post, we are going to make a start right here, right now. So here we are going to explore 3 EFL terms you should know: Interlanguage, Interference, and Fossilisation


Interlanguage is the linguistic system that underlies the language our learners produce.

In other words, your learners have their first language, and English is the target language, and the English they are capable of producing is their interlanguage.

Understanding interlanguage can be useful in many ways. Studying a student’s interlanguage will emphasise what a learner is producing rather than concentrating on error analysis, which is often what we do.

The interesting thing about interlanguage is that it is remarkably similar for learners regardless of their mother tongues. In other words, a Spanish-speaker and a Turkish-speaker may produce very similar language if they have similar levels of English. For example, they may follow the same developmental patterns when learning specific language structures.

At the same time, when it comes to error analysis, we see that learners who have the same or similar first languages are likely to produce the same errors. This is helpful when it comes to planning our lessons, as we are able to anticipate errors and plan appropriate lesson activities to counter those errors.

Read more: Encouraging Mistakes in the TEFL Classroom

pexels katerina holmes 5905962


Interference relates to problems that affect the learning of a new language, specifically caused by the learner’s first language.

It comes about as a result of the learner transferring aspects of their first language onto the second language. Even though this mostly happens when the learner is at a low level of the second language, it can actually happen at any stage in learning, when the learner makes assumptions about the language they do not know.

This makes sense when the first language and the second language are very different, but it is also a problem when the two languages are very similar, as learners may assume that words that look or sound similar have the same meaning or can be used in the same way when in fact they can’t.

False friends are such an example.

False friends are words that look and sound similar in two languages but have a completely different meaning. This is in contrast to cognates, which are words in different languages that come from the same family and so are related.

If you consider milk (English) and melk (Dutch) you can understand that they are cognates because they look and sound the same and they have the same meaning. However, embarrassed (English) and embarasado (Spanish) are false friends. Even though they look and sound similar, embarasado actually means pregnant!

Read more: An A-Z of the English Language


Fossilisation is when a language error becomes a habit in the second language.

Making mistakes in a foreign language is a natural part of the learning process and is to be expected and even encouraged. Language learners make mistakes all the time, but sometimes they will be corrected and other times they won’t. If the mistakes they are making do not impede communication in any way there is a chance they will go unnoticed, especially if these productions are not taking place in the EFL classroom. If this happens again and again, over time the learner will adopt this error into their language production without realising it is a mistake.

Fossilised errors can be extremely difficult to correct because they have been incorporated into a learner’s interlanguage. However, bringing a learner’s attention to the error and their production can help, as can doing activities focussed on that particular error.

Read more: Effective Error Correction

Don’t worry if this is all news to you, every day is an opportunity for learning! Now that you have a good grasp of the terms interlanguage, interference, and fossilization, you can move on to other terms you should know. When you have some free time, instead of automatically switching on Netflix, rather pick up a TEFL book or read a TEFL blog to keep you informed and educated on all things TEFL.

Get Social

Follow us on social networks, join our newsletter - get the latest news and early discounts

Sign up to our newsletter

Follow us on social networks, sign up to our e-newsletters – get the latest news and early discounts

Accreditation Partners

Product added to your cart

You have added to your cart:

Request call back

    Please leave your details below and one of our TEFL experts will get back to you ASAP:

    captcha Type characters on the left:

    Would you like us to update you on TEFL opportunities, jobs and related products & services?

    Yes, keep me updatedNo, but thanks anyway!

    Download the TEFL World Factbook

      Please enter your details in order to download the latest TEFL World Factbook.

      Would you like us to update you on TEFL opportunities, jobs and related products & services?

      Yes, keep me updatedNo, but thanks anyway!

      Thank you for downloading the TEFL World Factbook!

      If the TEFL World Factbook did not download
      > Click Here To Download <.

      Download the Online Teaching Guide

        Please enter your details in order to download our Online Teaching Guide.

        Would you like us to update you on TEFL opportunities, jobs and related products & services?

        Yes, keep me updatedNo, but thanks anyway!

        Thank you for downloading our Online Teaching Guide!

        If the Online Teaching Guide did not download
        > Click Here To Download <.