contradict
/ˌkän-trə-ˈdikt/
verb
to assert the contrary of : take issue with
to imply the opposite or a denial of
contradict a rumor
deny gainsay contradict contravene mean to refuse to accept as true or valid. deny implies a firm refusal to accept as true, to grant or concede, or to acknowledge the existence or claims of. gainsay implies disputing the truth of what another has said.
idiom
to say or do something that is opposite or very different in meaning to something else that one said or did earlier
The witness contradicted herself when she insisted she could identify the thief even though she had said that the night was too foggy to see clearly.