relating to a position of responsibility:
He visited China in his official capacity as America's trade representative.
Number Ten Downing Street is the British prime minister's official residence.
agreed to or arranged by people in positions of authority:
the official photos of the president's tour of India
The Queen will attend the official opening of the theatre in June.
There is to be an official inquiry into the incident.
If a piece of information is official, it has been announced publicly with authority:
Their engagement is now official.
Inflation has fallen below two percent, and that's official.
An official language is one that is used by the government of a country when making its laws, in official documents, etc.:
Arabic is the official language of about 20 countries.
There was a vote on which language should become the official one.