From Longman Dictionary of Contemporary Englishnative language/tonguenative language/tongueSLLthe language you spoke when you first learned to speak SYN first language English is not the native language for almost half of our overseas visitors. → native
Examples from the Corpus
native language/tongue• English is not his native language.• But dialect features are not errors in this sense at all, but are characteristics of a pupil's native language.• It is perfectly possible to communicate with little or no such similarity or else children would never learn their native tongue.• Some of the early researchers took a pessimistic view of what we would lose with the disappearance of native languages.• But for most of us our native tongue is alive and constantly shifting.• And as they learn their native language, they also use language to learn other things. 