Christ·mas (kr?s?m?s)n.1. A Christian feast commemorating the birth of Jesus.2. December 25, the day on which this feast is observed as a public holiday in many countries.3. Christmastide.[Middle English Cristemas, from Old English Cr?stes mæsse, Christ’s festival : Cr?st, Christ; see Christ + mæsse, festival; see Mass.]Christ?mas·sy, Christ?mas·y adj.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.Christmassy (?kr?sm?s?) adjof, relating to, or suitable for ChristmasCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014