Hi Alex! You are right. "Mother tongue" is a metaphorical English idiom used to refer to someone's native language. We don't usually say phrases like "my first tongue," "my second tongue," or "the tongue of my country," so the word "tongue" by itself is not necessarily interchangeable with "language." You could technically use the word "tongue" in this way in creative writing, but it is not common in casual daily conversations. "Mother tongue" is the complete idiom, metaphorically saying the person was raised to speak that language from birth. There are no "stupid" questions. (: Stay curious, and happy learning!

Hi Alex, I think "tongue" was used as a synonym for "language" more often in the past, but isn't used that way very much any more besides in this set phrase. So I wouldn't recommend saying something like "I speak the Russian tongue" these days. And by the way, I would suggest that you ignore certain people who answered your question rudely. There's no need to be so aggressive when someone just asked an innocent question as you did. You did nothing wrong.

Native speakers don't use "tongue" to mean "language" in everyday communication. This is a literary use that you might encounter in poem or old stories. The people who incorrectly say "mother tongue" or worse, "mother language" (totally wrong), are non-native speakers translating directly from their native language ("langue maternelle" in French, for example, or "родной язык" in Russian). The standard way to say which language you've been speaking since birth is: "My native language is..." You are right and they are mistakenly translating directly from their native language.

I don't think this is a ridiculous question either. In fact it's a very good one. It's related to the roots and the diversity of modern English A lot of English is derived from Latin and 'language' is derived from Latin... but 'tongue' does not from Latin, it comes from Germanic languages. So 'tongue' can be a synonym for 'language', but 'language' is NOT a synonym for 'tongue'(the physical part of the body). It's not difficult to see that confusion might arise. Especially if you are translating from a language like Italian where both 'language' and the physical body part 'tongue' are translated as 'lingua'. So we have a situation where there are different possible alternatives, and because English has been spoken in various different places around the world during those centuries different phrases have become more popular in different regions. My opinion is that 'native language' is most common in British English. And from the other answers to this question it seems that perhaps 'mother tongue' (which sounds quite unusual to me) might be more common in American English. I don't think that 'mother language' is commonly used, but I might be wrong, or it might become more widely used in the future. Unlike Latin, English is still evolving.

In Spanish (and probably the other Latin languages) tongue and language are the same thing, same word: lengua. La lengua maternal. La lengua de la boca. Je parle la langue anglais. In Russian language and tongue are the same word: язык. Говорю английский язык. In German you could you use 'Zunge" for the body part and language, although 'speech/ Sprache' is more common. This has a parallel in Old English ' to speak another tongue' , to speak in tongues, the mother tongue, to speak a foreign tongue. It's just that English imported more 'sophisticated' words from French/Latin but kept most of the old AS/Germanic words too.