Noun

1. Someone who puts an end to other's fun, especially harmless fun.
   • 1908, Edward Morgan Forster, A Room with a View, Chapter XIV,

     I know I am a sad spoilsport, but it would make me wretched.

   • 1912, George Bernard Shaw, Androcles and the Lion, Act II

     He looks a spoilsport. There are men in whose presence it is impossible to have any fun:

See also

• burst someone’s bubble, bust someone’s bubble
• make waves
• killjoy
• party pooper
• put a damper on
• rain on somebody’s parade
• rock the boat
• upset the applecart, upset someone’s applecart
• stick in the mud
• wet blanket