pin wrench or pinwrenchn (Tools) a wrench fitted with a cylindrical pin that registers in a hole in the part to be rotated, used to improve the application of the turning momentCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014pin? wrench` n. a wrench having a pin for insertion into the heads of certain bolts to drive them. Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.