jack-o'-lantern

Short definition from Wiktionary

Noun

1. 1
   A carved pumpkin whose top and stem have been cut out and interior removed, leaving a hollow shell that is then decorated to represent a face, illuminated from within by a candle. It is a symbol of Halloween.
2. 2
   A carved pumpkin whose top and stem have been cut out and interior removed, leaving a hollow shell that is then decorated to represent a face, illuminated from within by a candle. It is a symbol of Halloween: A similar item made from a turnip
3. 3
   A will o' the wisp.