Verb

To contradict; to withsay; to deny, refute; to controvert; to dispute; to forbid.

*

* 1902 , , The Hound of the Baskervilles :

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.

* {{quote-news

, date=2012-07-07 , first= , last= , author= , authorlink= , coauthors= , title= Griffith acted, and lived, by Golden Rule , newspaper=The Post and Courier , city=Charleston , publisher=Evening Post Publishing , quotee= citation , page=5, Features , passage=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. }}

Verb

To renounce or deny something, especially under oath.

* Shakespeare

I do forswear her.

* Dryden

Like innocence, and as serenely bold / As truth, how loudly he forswears thy gold!

To commit perjury.