early 15c., "piece of cloth of full size," as opposed to a piece cut out for a garment; figurative sense first attested 1570s.
Online Etymology Dictionary, © 2010 Douglas Harper
Examples from the Web for whole cloth
Whole-cloth fabrication on the level perpetrated by folks like Stephen Glass or James Frey is of course beyond the pale.Speak, Faulty Memory: Why Memoir Writing Is Harder Than You Think
April 3, 2013