heritage language
Linguistics term for a language learned at home during childhood that is not the dominant language of the wider society.
Japanese language education as a heritage language is attracting attention.
第二言語 is a second language learned after the first language, often in a formal setting, whereas 継承語 is acquired in a home environment.
Compound of 継承 (inheritance) and 語 (language). The term is a direct translation of the English 'heritage language' used in linguistics.