fiasco UK /fiˈæs.kəʊ/US /fiˈæs.koʊ/ noun3 •A sudden or unexpected failure.The event turned into a complete fiasco when the power went out.His speech was a fiasco that left the audience confused. •A ludicrous or humiliating situation. Some effort that went quite wrong. •A wine bottle in a (usually straw) jacket. formsfiaschi · fiasci · fiascoes · fiascos