first language

/F ER1 S T L AE1 NG G W AH0 JH/
noun
  1. 1

    The first language one is taught to speak; one's native language.

    โ€œShe was born and raised in France, although her first language is Portuguese because her parents are from Brazil.โ€

  2. 2

    The language one feels most comfortable and capable with.

Source: https://en.wiktionary.org/wiki/first%20language