ep·i·du·ral (?p??-do?or??l, -dyo?or?-)adj. Located on or over the dura mater.n. An injection into the epidural space of the spine.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.epidural (??p??dj??r?l) adj (Anatomy) Also: extradural upon or outside the dura matern (Surgery) a. injection of anaesthetic into the space outside the dura mater enveloping the spinal cordb. anaesthesia induced by this method[C19: from epi- + dur(a mater) + -al1]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014ep?i?du?ral (??p ??d??r ?l, -?dy??r-) adj. 1. situated on or outside the dura mater. 2. of or pertaining to the insertion of an anesthetic into the lumbar spine in the space between the spinal cord and dura mater, which blocks sensation in the body from that point downward: epidural anesthesia. n. 3. an epidural injection of anesthesia; spinal anesthesia. [1880?85; epi- + dur (a mater) + -al1] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.