out·rid·er (out?r??d?r)n.1. A guide; an escort.2. One that goes in advance; a forerunner.3. A mounted attendant who rides in front of or beside a carriage.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.outrider (?a?t?ra?d?) n1. a person who goes ahead of a car, group of people, etc, to ensure a clear passage2. a person who goes in advance to investigate, discover a way, etc; scout3. a person who rides in front of or beside a carriage, esp as an attendant or guard4. US a mounted herdsmanCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014out?rid?er (?a?t?ra? d?r) n. 1. a mounted attendant riding before or beside a carriage. 2. a mounted rider who accompanies a racehorse to the post. 3. a person who goes in advance. [1520?30] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.