Floyd Mayweather just got ripped a new one in appeals court -- with a panel of judges saying there's a ton of evidence showing the boxer lied to Katie Couric in a '15 interview about his domestic violence case.
Remember, Floyd's ex, Josie Harris, is suing Floyd for defamation ... claiming the boxer fudged the facts and lied about her to Couric when discussing his 2010 domestic violence arrest.
In the interview, Floyd told Couric he did NOT "kick, stomp and beat someone" .