official language
Refers to a language designated by law or regulation for official use in a country, region, or organization.
Switzerland recognizes four official languages.
公用語 is the language(s) officially designated for government and public use, whereas 標準語 refers to the codified standard form of a language itself, regardless of its legal status.
official languages of the UN
Compound of 公用 (official use) + 語 (language).