official language
A language given official status in a region by law, which may be one of several and need not be the most widely spoken.
An official language is one a region has given legal standing, normally for administration, legislation and the courts.
A region can have more than one. Switzerland recognizes four, South Africa twelve, and a bilingual city may run its street signage in two of them at once.
Official status and everyday use are different facts. A language can be official while a minority speaks it, and the most spoken language in a place may hold no official status at all.
