British (adj.)

Old English Bryttisc "of or relating to (ancient) Britons," from Bryttas "natives of ancient Britain" (see Briton). Meaning "of or pertaining to Great Britain" is from c. 1600; the noun meaning "inhabitants of Great Britain" is from 1640s. British Empire is from c. 1600. First modern record of British Isles is from 1620s. British English as the form of the English language spoken in Britain is by 1862 (George P. Marsh). Related: Britishness.

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Definitions of British from WordNet
British (n.)
the people of Great Britain;
Synonyms: British people / Brits
British (adj.)
of or relating to or characteristic of Great Britain or its people or culture;