English version

mother tongue in Languages topic

From Longman Dictionary of Contemporary Englishmother tongueˌmother ˈtongue noun [countable] especially British English  SLLyour mother tongue is the first and main language that you learnt when you were a child syn native language/tongue children for whom English is not their mother tongue
Examples from the Corpus
mother tongueMore than one-fifth of the population had German as their mother tongue.