The Collaborative International Dictionary of English v.0.48:
Briticism \Brit"i*cism\, n. A word, phrase, or idiom peculiar to Great Britain; any manner of using a word or words that is peculiar to Great Britain. [1913 Webster]WordNet (r) 3.0 (2006):
Briticism n 1: an expression that is used in Great Britain (especially as contrasted with American English) [syn: Anglicism, Briticism, Britishism]