Adjective with shared origins and formal definitions with "bright" but with geographically varied differences in colloquial use:
A. United States: Intelligent, particularly in innovative or unique ways. Often used sarcastically for shining examples of outstanding and innovative stupidity.
B. Britain: Of very high quality in any way, in a manner or circumstance where that quality stands out.
C. Canada, Australia, and New Zealand: Predominantly used in the sarcastic mode of the US sense.
US(direct): The marketing of sage as a recreational drug by calling it 'Sticky Purple Salvia' was brilliant.
US(sarcastic): Rick Santorum
is brilliant to answer questions about contraception.
UK: The Doctor
frequently says 'You're brilliant!" to people who have no idea why.
Canada: With P.M. Harper's party leading an unstable minority government, his strategy of looking to George Bush as a role model is brilliant.