To flummox someone means to confuse or perplex them so completely that they don't know what to say or do next. When you're flummoxed, you're stumped, baffled, caught completely off guard with no idea how to respond.

Imagine your math teacher suddenly asks the class to explain a concept from next week's lesson that nobody has learned yet. You might sit there flummoxed, unable even to begin an answer. Or picture trying to help your little brother with homework on a subject you've never studied. The strange terminology and unfamiliar problems might leave you totally flummoxed.

The word has a playful, almost comical quality to it. When someone is flummoxed, they often show it: mouth slightly open, eyes wide, perhaps scratching their head. A mystery novel might describe a detective flummoxed by a suspect's airtight alibi. A mechanic might be flummoxed by a car that keeps breaking down for no apparent reason.

You can also flummox someone on purpose. A clever riddle might flummox your friends. A magician's best tricks can flummox the audience, leaving them wondering, “How did they do that?”