bloomer

1. (informal, originally Australia) A large or embarrassing mistake; blunder.Examples: "What's more, I claim that Elmer's biggest mistake wasn't the one he made at Cedarville before six thousand witnesses. His prize bloomer was pulled in Hoboken before three witnesses"; ""You know," pursued Reggie seriously, "I think you are making the bloomer of a lifetime over this hat-swatting chappie. You've misjudged him. He's a first-rate sort.[…]"; "In 1933, four years before his death, Rutherford said, firmly and explicitly, that he didn't believe the energy of the nucleus would ever be released—nine years later, at Chicago, the first pile began to run. That was the only major bloomer in scientific judgment Rutherford ever made."Synonyms: aberration, barbarism, bloomer, blooper, blunder, boner, boo-boo, breakinformal

2. (figurative) One who blooms, matures, or develops.Examples: "She was a late bloomer."figuratively