yestermorn adverb 1noun 1 adverb1 •(no longer used) During the morning of yesterday; yesterday morning.But yester-morn, whose house was so great, so flourishing as Manfred's? — 1764 noun1 •(no longer used) The morning of yesterday.The sad accident at Lyme was soon the prevailing topic; and on comparing their latest accounts of the invalid, it appeared that each lady dated her intelligence from the same hour of yester morn, […] — 1817
