Halloween

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun October 31, celebrated in the United States, Canada, and the British Isles by children going door to door while wearing costumes and asking for treats and playing pranks.

from The Century Dictionary.

• noun The evening of October 31st, as the eve or vigil of All-hallows or All Saints' day.

from the GNU version of the Collaborative International Dictionary of English.

• noun Scot. The evening preceding Allhallows or All Saints' Day (November 1); also the entire day, October 31. It is often marked by parties or celebrations, and sometimes by pranks played by young people.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The eve of All Hallows' Day; 31st October; celebrated (mostly in the United Kingdom, Canada, United States and Ireland) by children going door-to-door in costume and demanding candy with menaces.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the evening before All Saints' Day; often devoted to pranks played by young people
• noun the evening before All Saints' Day; often devoted to pranks played by young people