UKO'd Share definition Flag Alternative acronym for "Brexit" Brexit is such an overused term for Britain's vote to leave the E.U. - I'd say instead the vote basically UKO'd Britain from the E.U.!! UK knockout! UKO'd by Sushiray June 29, 2016 0 0 Get merch Get the UKO'd mug. Buy Now — $32.95 See more merch