well-de·fined (w?l?d?-f?nd?)adj.1. Having definite and distinct lines or features: a well-defined silhouette.2. Accurately and unambiguously stated or described: a well-defined argument.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.well-defined adj (well defined when postpositive) clearly delineated, described, or determinedCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014well?-defined? adj. sharply or clearly stated, outlined, described, etc.: a well-defined character; a well-defined boundary. [1695?1705] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.