(informal) An error; a mistake in the performance of an action.
1962 November 6, Richard Nixon, “Gentlemen, this is my last press conference”, 2008, Rick Perlstein (editor), Richard Nixon: Speeches, Writings, Documents, page 111,
I made a talk on television, a talk in which I made a flub—one of the few that I make, not because I′m so good on television but because I′ve been doing it a long time. I made a flub in which I said I was running for governor of the United States.
(US, Australia, slang) A fold of fat.
verb
(informal, transitive) To goof, fumble, or err in the performance of an action.