Definition of "yestermorn"

But yeſter-morn, whoſe houſe was ſo great, ſo flouriſhing as Manfred's?

1764 December 24 (indicated as 1765), Onuphrio Muralto, translated by William Marshal [pseudonyms; Horace Walpole], chapter II, in The Castle of Otranto, […], London: […] Tho[mas] Lownds […], page 70

"That, Clara," I said, "is the gate, that the street which yestermorn your father rode up."

1826, [Mary Shelley], chapter III, in The Last Man. […], volume II, London: Henry Colburn, […], page 88

Kate, I must make a confession... I, yestermorn, I took Caleb to The Wood.

2015, Robert Eggers, The Witch (motion picture), spoken by William (Ralph Ineson)

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 (date written), [Jane Austen], chapter I, in Persuasion; published in Northanger Abbey: And Persuasion. […], volume IV, London: John Murray, […], 20 December 1817 (indicated as 1818), page 13

By the wisdom of the centuries I speak— / To the tune of yestermorn I set the truth— / I, the joy of life unquestioned—I, the Greek— / I, the everlasting Wonder Song of Youth!

1896, Rudyard Kipling, “[The Seven Seas.] The Song of the Banjo.”, in The Seven Seas, London: Methuen & Co. […], page 84