noon·day (no?on?d??)n. Midday; noon.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.noonday (?nu?n?de?) na. the middle of the day; noonb. (as modifier): the noonday sun. Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014noon?day (?nun?de?) adj. 1. of or at noon or midday: the noonday meal. n. 2. midday; noon. [1525?35] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.