word square definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
a square made of letters so arranged that they spell the same words in the same order horizontally and vertically
word square definition by American Heritage Dictionary
A set of words arranged in a square such that they read the same horizontally and vertically. Also called acrostic.