official language
Formal term for a language designated as official by a government or organization. Often used in legal, political, or institutional contexts. Compare with 公用語, which is more common in everyday usage.
See also: 公用語
In that country, French is established as the official language.
The choice of an official language is an issue deeply tied to national identity.
公用語 is the more common and general term for 'official language'. 公用言語 is a formal, somewhat technical synonym, often used in legal or academic contexts.
Compound of 公用 (official use) + 言語 (language).