Contradict
Part of speech: verb
Definition: To speak against; to forbid. To deny the truth of (a statement or statements). To make a statement denying the truth of the statement(s) made by (a person).
Example sentence: We have but one flag, one country; let us stand together. We may differ in color, but not in sentiment. Many things have been said about me which are wrong, and which white and black persons here, who stood by me through the war, can contradict.
Controvert
Part of speech: verb
Definition: To dispute or argue using reason.To be involved or engaged in controversy.