1. To contradict; to deny what another says; to dispute.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• ganway,
• gainan,
• cainsaw,
• againsy,
• gaina,
• fansay,
• gainad,
• gainesay,
• gainsey,
• gainsai,
• gansaw,
• gainsaie,
• Gainsayd,
• gainsaye,
• gannsa,
• Goosary,
• geareey,
• gansah,
• tannsae,
• gainstt

• gangsaw,
• Gains,
• gaywings,
• gangway,
• ganesh,
• Gaines,
• GANS,
• gang,
• gayness,
• ganz,
• ganja,
• gangi,
• gansu,
• ganesha,
• ganesa,
• games.

The adverb form of "gainsay" is "gainsayingly".

The adjective form of the word "gainsay" is "gainsaying".