vitiate

Etymology

PIE word *dwóh₁ From Latin vitiātus, the perfect passive participle of vitiō (“damage, spoil”), from vitium (“vice”).

verb

1. (transitive) To spoil, make faulty; to reduce the value, quality, or effectiveness of something.
   The least admixture of a lie, -- for example, the taint of vanity, the least attempt to make a good impression, a favorable appearance, -- will instantly vitiate the effect. 1838, Ralph Waldo Emerson, An Address delivered before the Senior Class in Divinity College, Cambridge, Sunday evening, 15 July, 1838
   ‘Mr Rose,’ says the Physician, ‘this man was brought to us from Russia. Precisely such a case of vitiated judgment as I describe at length in my Treatise on Madness. Mayhap you have read it?’ 1997, Andrew Miller, Ingenious Pain
   Unfortunately, as Anderson and Sørenson (1996) and Bowsher (2002) document, instrument proliferation can vitiate the test. 2007 August, David Roodman, “A Short Note on the Theme of Too Many Instruments”, in Center for Global Development Working Paper 125, page 9
   We have examined with care all known negative feedback mechanisms, such as increase in low or middle cloud amount, and have concluded that the oversimplifications and inaccuracies in the models are not likely to have vitiated the principal conclusions that there will be appreciable warming. 2010, Naomi Oreskes, Erik M. Conway, quoting J. Charney et al., Carbon Dioxide and Climate[…], National Research Council, 1979, quoted in Merchants of Doubt
2. (transitive) To debase or morally corrupt.
   The robber does not intentionally vitiate people, but the governments, to accomplish their ends, vitiate whole generations from childhood to manhood with false religions and patriotic instruction. 1890, Leo Tolstoy, The Slavery of Our Times
3. (transitive, archaic) To violate, to rape.
   ‘Crush the cockatrice,’ he groaned, from his death-cell. ‘I am dead in law’ – but of the girl he denied that he had ‘attempted to vitiate her at Nine years old’; for ‘upon the word of a dying man, both her Eyes did see, and her Hands did act in all that was done’. 1965, John Fowles, The Magus
4. (transitive) To make something ineffective, to invalidate.
   […]all the hinges of the animal frame are subverted, every animal function is vitiated; the carcass retains but just life enough to make it capable of suffering. 1734, William Stukeley, Of the Gout, page 78
   After the trials, Turkey's secular elite was completely vitiated. September 2, 2011, Dexter Filkins, “Turkey's Thirty-Year Coup”, in The New Yorker