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.
1. indicating the day before today: yesterday.
2. indicating a period of time before the present one: yesteryear.
[Old English geostran; compare German gestern, Latin hesternus of yesterday]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
of or pertaining to yesterday (usu. used in combination): yesternight.
[1570–80; extracted from yesterday]
a combining form occurring in words that denote a time one period prior to the present period, the nature of the period being specified by the second element of the compound: yesteryear.
(Old English geostran, c. Old High German gestre; akin to Latin hesternus of yesterday]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.