Verb

(vitiat)

to spoil, make faulty; to reduce the value, quality, or effectiveness of something

*1851 ,

There was excellent blood in his veins—royal stuff; though sadly vitiated , I fear, by the cannibal propensity he nourished in his untutored youth.

* 1997': ‘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?’ — Andrew Miller, ''Ingenious Pain

to debase or morally corrupt

*1890 , Leo Tolstoy,

*: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.

(archaic) to violate, to rape

* 1965': ‘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’. — John Fowles, ''The Magus

to make something ineffective, to invalidate

*{{quote-book

, author = , title = , year = 1734 , page = 78 , passage = ...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. }}

Verb

(enfeebl)

To make feeble.

* 2014 , Michael White, " Roll up, roll up! The Amazing Salmond will show a Scotland you won't believe", The Guardian , 8 September 2014:

In the face of enfeebled , self-harming opposition on both sides of the border (and a miserable economic recession on both sides too) he has performed brilliantly.

* 1774, Dr Samuel Johnson, Preface to the Works of the English Poets , J. Nichols, Volume II, Page 130,

"...the gout, with which he had long been tormented, prevailed over the enfeebled powers of nature."