Definition of "undeceive"

[I]t is a deed of higheſt charitie to help undeceive the people, and a vvork vvorthieſt your autoritie, in all things els authors, aſſertors and novv recoverers of our libertie, to deliver us, the only people of all Proteſtants left ſtill undeliverd, from the oppreſſions of a Simonious decimating clergie; […]

1659, J[ohn] M[ilton], “To the Parlament of the Commonwealth of England with the Dominions therof”, in Considerations Touching the Likeliest Means to Remove Hirelings out of the Church. […], London: […] T[homas] N[ewcombe] for L[ivewell] Chapman […]

[…] Marcasites, I say, being thus fitted to delude the unskilful, I have had much ado to undeceive some, that brought or sent me them from America, of the pleasing Confidence they had entertained, that these promising Fossiles were Lumps of rich Ore of Gold, or Silver.

1690, Robert Boyle, “A Previous Hydrostatical Way of Estimating Ores”, in Medicina Hydrostatica‎, London: Samuel Smith, Section V, p. 168

Undeceived in her expectations and chilled in her hopes, the heart of Cecilia no longer struggled to sustain its dignity, or conceal its tenderness […]

1782, [Frances Burney], chapter IX, in Cecilia, or Memoirs of an Heiress. […], volume III, London: […] T[homas] Payne and Son […], and T[homas] Cadell […], book VI, page 318

If you think that this loss has broken my heart undeceive yourself, for such as I live years in an hour and show no sign.

1863 January 3, Louisa May Alcott, chapter 1, in Pauline’s Passion and Punishment: Frank Leslie’s Illustrated Newspaper, volume XV, number 379, page 229

Early every morning she made something she called (and believed to be) coffee for George, and he was gallant enough not to undeceive her.

1918, Booth Tarkington, chapter XXXIII, in The Magnificent Ambersons, Garden City, N.Y.: Doubleday, Page & Company, page 467