sex linkagen. The condition in which a gene responsible for a specific trait is located on a sex chromosome, resulting in sexually dependent inheritance of the trait.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.sex linkage n (Genetics) genetics the condition in which a particular gene is located on a sex chromosome, esp on the X-chromosome, so that the character controlled by the gene is associated with either of the sexes ?sex?linked adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014