ship·lap (sh?p?l?p?)n. Wooden siding rabbeted so that the edge of one board overlaps the one next to it in a flush joint.ship?lapped? adj.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.shiplap (???p?læp) or shiplappingna wooden board that has been rabbeted so that the edges of each board overlap the edges of adjacent boards to create a flush and stable jointCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014ship?lap (???p?læp) n. 1. an overlapping joint, as a rabbet, between two boards joined edge to edge. 2. boarding joined with such overlapping joints. [1850?55] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.