- a block having two sheaves or pulleys.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for double block
An iron thimble, large enough to hook the double-block of a side or train tackle, is spliced into the end of each purchase-fall.Ordnance Instructions for the United States Navy.
Bureau of Ordnance, USN