Dictionary.com
definitions

double spread

noun
  1. any pair of facing pages in a completed book, magazine, etc.
  2. a picture, advertisement, etc., occupying two facing pages.

Origin of double spread

First recorded in 1955–60
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for double spread

double spread

noun
  1. printing two facing pages of a publication treated as a single unit
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