a sloping surface against which the end of an arch rests.
a stone, course of masonry, or the like, presenting such a surface.
Origin of skewback
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
the sloping surface on both sides of a segmental arch that takes the thrust
one or more stones that provide such a surface
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012