out of whole cloth
From pure fabrication or fiction. This expression is often put as cut (or made) out of whole cloth, as in That story was cut out of whole cloth. In the 15th century this expression referred to something fabricated from cloth that ran the full length of the loom. However, by the 1800s it was common practice for tailors to deceive their customers and, instead of using whole cloth, actually make garments from pieced goods. Their advertising slogan, "cut out of whole cloth," thus came to mean "made up, false."