A fiasco is a complete and often embarrassing failure, especially one that happens in a public or dramatic way. When a school play turns into a fiasco, maybe the curtain falls on the actors, someone forgets all their lines, and the sound system breaks, all in front of a packed auditorium. When a surprise party becomes a fiasco, the birthday person arrives early, the cake gets dropped, and nobody remembered to bring decorations.

What makes something a fiasco rather than just a regular failure is the spectacular, almost comical way things go wrong. A science experiment that doesn't work is a failure. A science experiment where the volcano erupts too early, covers the ceiling in foam, sets off the fire alarm, and evacuates the whole school: that's a fiasco.

The word usually suggests that despite someone's best intentions or careful planning, everything fell apart in an almost ridiculous way. A fiasco is memorable precisely because it's so completely, dramatically unsuccessful.