Englishgainsay
verb
formal
it was difficult to gainsay his claim:
deny, dispute, disagree with, argue with, dissent from, contradict, repudiate, declare untrue, challenge, oppose, contest, counter, fly in the face of;
disprove, debunk, explode, discredit, refute, rebut, brush aside;
informal shoot full of holes, shoot down (in flames);
Law disaffirm;
rare controvert, confute.
▷antonyms confirm.
gainsay Oxford Dictionary of English