Someone's first language is the language that they learned first and speak best; used especially when someone speaks more than one language. the language that you first learn as a child = native language/tongue, mother tongue mother tongue second language
one's native language; the language learned by children and passed from one generation to the next
politically correct language referring to disabilities by avoiding adjectives or the copula
people first language, which refers to the person first and the disability second: Americans with disabilities, for example, rather than disabled Americans, letter to the editor of BusinessWeek, published in Issue 3059 (1988).