Meaning of BRITISH in English

I. Brit ‧ ish 1 /ˈbrɪtɪʃ/ BrE AmE adjective

[ Language: Old English ; Origin: Brettisc 'of ancient Britain' , from Bret 'British person' , from a Celtic language ]

relating to Britain or its people:

the British government

a British-born scientist

—Britishness noun [uncountable]

II. British 2 BrE AmE noun

the British [plural] people from Britain

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.