第だい一いち言げん語ご

noun

first language; native language

Refers to the language a person learns first, often synonymous with 'mother tongue'. Used in linguistics and everyday contexts.

• 彼かれの第だい一いち言げん語ごは日本にほん語ごです。

  His first language is Japanese.

• 第だい一いち言げん語ごの習しゅう得とくは幼よう児じ期きに起おこる。

  First language acquisition occurs in early childhood.