birth·mark (bûrth?märk?)n. A skin lesion, such as a nevus or angioma, that is present at birth.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.birthmark (?b????m??k) n (Gynaecology & Obstetrics) a blemish or new growth on skin formed before birth, usually brown or dark red; naevusCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014birth?mark (?b?r??m?rk) n. a minor disfigurement or blemish on a person’s skin at birth; nevus. [1570?80] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.