gainsay

Etymology

From Middle English gainsayen, ȝeinseggen (“to say against, say in opposition to”), equivalent to gain- + say. Compare Old Danish gensige (“to speak against; gainsay”), Swedish gensaga (“a speaking against; protest”).

verb

1. (transitive, formal) To say something in contradiction to.
   […]vve are able with playne demonſtration to proue, and vvith reaſon to perſvvade that in tymes paſt our fayth vvas alike, that then vve preached thinges correſpondent vnto the forme of faith already publiſhed of vs, ſo that none in this behalfe can repyne or gayneſay vs. 1577, Socrates Scholasticus [i.e., Socrates of Constantinople], “Constantinus the Emperour Summoneth the Nicene Councell, it was Held at Nicæa a Citie of Bythnia for the Debatinge of the Controuersie about the Feast of Easter, and the Rootinge out of the Heresie of Arius”, in Eusebius Pamphilus, Socrates Scholasticus, Evagrius Scholasticus, Dorotheus, translated by Meredith Hanmer, The Avncient Ecclesiasticall Histories of the First Six Hundred Yeares after Christ, Wrytten in the Greeke Tongue by Three Learned Historiographers, Eusebius, Socrates, and Euagrius. …, book I (The First Booke of the Ecclesiasticall Historye of Socrates Scholasticvs), imprinted at London: By Thomas Vautroullier dwelling in the Blackefriers by Ludgate, →OCLC, page 225
   The supreme court, therefore, may assume jurisdiction over subjects and between parties, not allowed by the constitution, and there is no power in the federal government to gainsay it. 1840, Abel Upshur, A Brief Enquiry into the Nature and Character of our Federal Government, Campbell, page 84
   So she had, cried Scrooge. You’re right. I will not gainsay it, Spirit. God forbid! 1843, Charles Dickens, A Christmas Carol
   Know then that in the time of the Great Rebellion (the history of which by the learned Lord Clarendon I most earnestly commend to your attention) this Manor of Baskerville was held by Hugo of that name, nor can it be gainsaid that he was a most wild, profane, and godless man. 1902, Arthur Conan Doyle, The Hound of the Baskervilles
   And there was something childlike about Griffith, too, even in his Matlock days, as a deceptively sharp 'simple country lawyer,' a big-kid boyishness that did not mask his intelligence or gainsay his authority. 2012-07-07, “Griffith acted, and lived, by Golden Rule”, in The Post and Courier&p_product=CPCB), Charleston: Evening Post Publishing, page 5, Features