first language

The first language a human being learns to speak is his/her native language. He/She is a native speaker of this language according to Leonard Bloomfield A first language or native language is a basis for sociolinguistic identity.In linguistics first language can be referred to as arterial language, mother tongue, or L1.
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Noun
1. one's native language; the language learned by children and passed from one generation to the next
(synonym) mother tongue, maternal language
(hypernym) natural language, tongue