There are four meanings listed in OED's entry for the verb gainsay. See 'Meaning & use' for definitions, usage, and quotation evidence.

To contradict; to oppose in words; to deny or declare not to be true what another says; to controvert; to dispute; applied to persons, or to propositions.

Gainsay definition: To declare to be false; deny.

gainsaying: Opposition, especially in speech; refusal to accept or believe something; contradiction; denial.

(often used in negative sentences) to say that something is not true; to disagree with or deny something synonym deny Nobody can gainsay his claims.

gainsay. verb. To refuse to admit the truth, reality, value, or worth of: contradict, contravene, controvert, deny, disaffirm, negate, negative, oppugn. Law: ...

1. (formal) Deny or contradict (a fact or statement) 2. Speak against or oppose (someone) Examples of Gainsay in a sentence

1. to deny; dispute; contradict. 2. to speak or act against; oppose. [1250–1300; Middle English gainsaien; see again, say]. gain ...

Gainsaying. GAINSA'YING, participle present tense Contradicting; denying; opposing.

GAINSAID meaning: 1. past simple and past participle of gainsay formal 2. past simple and past participle of gainsay…. Learn more.