April Fools' Day
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio.
April 1; All Fools' Day, when practical jokes are played on the unsuspecting
Used by arrangement with John Wiley & Sons, Inc.
nounThe American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
April 1, celebrated in various countries, including the United States and Great Britain, and marked by the playing of practical jokes. Also called All Fools' Day.