The Collaborative International Dictionary of English v.0.48:

Brits \Brits\ n.
   the people of Great Britain. [informal]

   Syn: British, British people, the British.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Brits
    n 1: the people of Great Britain [syn: British, British
         people, Brits]