Fiasco/fiˈæskəʊ/ Definition 1 of 1Pro Tip 1/3Negative Outcome Used when something is a lot worse than expected, not just a small mistake. After so much planning, the event was a fiasco. Pro Tip 2/3Not Formal More common in casual conversation or informal writing, not in official reports. I tried baking a cake, but it was a complete fiasco. Pro Tip 3/3Strong Emphasis Often emphasizes that the failure had significant negative emotions or impact. His first stage performance turned into a fiasco.