matchboard 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.
any of a number of identical boards with a tongue formed along one edge and a groove cut along the other so that the tongue of one can be fitted into the groove of the next, as in making floors
also matched board
matchboard definition by American Heritage Dictionary
A board cut with a tongue on one side and a matching groove on the other to fit with other boards of similar cut.