name dayn. The feast day of the saint after whom one is named.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.name day n 1. (Roman Catholic Church) RC Church the feast day of a saint whose name one bears 2. (Stock Exchange) another name for ticket day Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014name? day` n. 1. the feast day of the saint after whom a person is named. 2. the day on which a person is christened. [1715?25] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.